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Full text of "Gems and gem minerals"

GEMS AND GEM MINERALS 




GEMS AND GEM 
MINERALS 



OLIVER CUMMINGS FARRINGTON, PH.D. 

CURATOR OF GEOLOGY, FIELD COLUMBIAN MUSEUM 



" FOR LITERAL TRUTH OF YOUR JEWELS THEMSELVES, 
ABSOLUTELY SEARCH OUT AND CAST AWAY ALL MANNER OF 
FALSE OR DYED OR ALTERED STONES. * * * AND. AS A 
PIECE OF TRUE * * * KNOWLEDGE, LEARN TO KNOW 
THESE STONES WHEN YOU SEE THEM UNCUT." 

BUSKIN 




CHICAGO 

A. W. MUMFORD, PUBLISHER 

1903 



CC 



COPYRIGHT, 1903 

BY OLIVER CDMMINGS FARRINGTON 
CHICAGO 



f)c Eakest'tie $rrse 

DONNELLEY & SONS COMPANY 
CHICAGO 



CONTENTS 



NATURE OF GEMS - 1 

OCCURRENCE OF GEMS - 4 

MINING OF GEMS - 8 

COLOR OF GEMS - 13 

LUSTER 16 

HARDNESS 17 

SPECIFIC GRAVITY - 19 

OPTICAL QUALITIES 26 

ELECTRICAL PROPERTIES, PHOSPHORESCENCE, AND FLUORESCENCE 34 

CRYSTAL FORM - 37 

CUTTING AND MOUNTING 41 

VALUATION AND PRICE - 50 

IMITATION GEMS AND How TO DETECT THEM 54 

SUPERSTITIONS EEGARDING GEMS 57 

BIRTH-STONES - 61 

DIAMOND 66 

CORUNDUM - 88 

SPINEL - - 95 

BERYL 98- 

EUCLASE - 104 

PHENACITE - 105 

CHRYSOBERYL - - 106 

ZIRCON 109 

TOURMALINE - - 111 

LEPIDOLITE - - 117 

SPODUMENE - - - 118 

TOPAZ 119 

CYANITE - - - 123 

ANDALUSITE - 124 

STAUROLITE - 126 

GARNET - 127 

CHRYSOLITE -- ---132 

EPIDOTE - - - - 134 

VESUVIANITE - - - - - - - -135 

IOLITE - - - - - - -136 

EUTILE .... -.-. 137 




33 



PAGE 

TlTANITE - 138 

AXINITE - - - 139 

SAMARSKITE, GADOLINITE, ALLANITE, FERGUSONITE, POLYCRASE, AND 

EUXENITE - 140 

QUARTZ - - 141 

OPAL 159 

JADE - 165 

DIOPSIDE - 168 

HYPERSTHENE AND BRONZITE - - 169 

TURQUOIS - 170 

VARISCITE - 174 

CALLAINITE - 174 

FELDSPAR - 175 

OBSIDIAN - 180 

MOLDAVITE - 183 

APATITE - 185 

FLUORITE - 186 

HEMATITE - 188 

PYRITE - - 189 

CHLORASTROLITE - - - 191 

THOMSONITE - - - - -192 

PREHNITE - - 193 

EHODONITE - - - 194 

ZOISITE ... - 195 

PRECIOUS SERPENTINE - - 195 

MALACHITE - - - 197 

CHRYSOCOLLA - - - 199 

DIOPTASE - .... 200 

LAPIS LAZULI - - - 201 

SMITHSONITE 203 

ALABASTER - - - 204 

AMBER - - 205 

JET 210 
PEARL 

PRECIOUS CORAL - - - - - -221 



vi 



HALF-TONES AND LINE ENGRAVINGS 

PAGE 

ANDALUSITE, SECTION OF CRYSTAL OF - 124 

AXINITE - - 139 

BERYL, CRYSTAL FORMS OF - 99 

BRILLIANT CUT, VIEWS OF 44 

CABOCHON CUT, VIEWS OF - 46 

CEYLONESE GEM CUTTER, A 42 

CONCENTRATION OF GEM MINERALS UPON A BEACH - 6 

CORUNDUM MINE, NORTH CAROLINA 93 

CRYSTAL AXES - 38 

CUBE, OCTAHEDRON, DODECAHEDRON, AND TRAPEZOHEDRON - 39 

CUTTING AGATES AT OBERSTEIN - 48 

DIAMOND BRILLIANTS, EXACT SIZES OF - - 51 

DIAMOND CRYSTALS, COMMON FORMS OF - 67 

DIAMOND DIGGING NEAR DIAMANTINA, BRAZIL - 4 

DIAMOND MINES OF KIMBERLY, 1872 - 81 

DIAMOND MINING, Rio JEQUETINHONHA, BRAZIL - 77 

DISTORTION OF CUBICAL CRYSTAL - 37 

DREDGING PRECIOUS CORAL - - 221 

FAIRY STONES - - 126 

FLUORITE, CRYSTAL FORMS OF - - 186 

GARNET, CRYSTAL FORMS OF - 127 

GLACIAL MAP OF THE GREAT LAKES REGION - - - 89 

HEXAGONAL PRISM AND PYRAMID - 40 

INSTRUMENT FOR EXAMINING GEMS IN POLARIZED LIGHT - 32 

MAP OF INDIA, SHOWING DIAMOND FIELDS - 71 

MAP OF DIAMOND FIELDS OF BRAZIL 76 

MINING OPAL, NEW SOUTH WALES - - - 163 

MOLDAVITE PEBBLES - 183 

MOSS-AGATE, INDIA - - - 151 

NICOL PRISM, CONSTRUCTION OF - - - - - 30 



OBSIDIAN CLIFF, YELLOWSTONE PARK - 181 

OPAL MINES, NEW SOUTH WALES - - 163 

PATH OF RAY IN DIAMOND CUT AS A BRILLIANT - - -29 

PATH OF RAYS PASSING FROM DENSE TO RARE MEDIUM - 28 

PEARLS, EXACT SIZES OF, FROM 2 TO 30 GRAINS - - 219 

PREMIER DIAMOND MINE, SOUTH AFRICA - 8 
PRELIMINARY CONCENTRATION OF DIAMOND-BEARING GRAVEL - 78 

PYRITE, CRYSTAL FORMS OF 189 

QUARTZ, CRYSTAL FORMS OF - - - 142 

QUARTZ, CRYSTAL FORMS OF, PRODUCED BY DISTORTION - 38 

REFLECTION OF LIGHT, DIAGRAM ILLUSTRATING - - 26 

REFRACTION OF LIGHT, DIAGRAM ILLUSTRATING - 28 

REMARKABLE DIAMONDS - 72 

ROSE CUT - 46 

RUBY-BEARING GRAVEL, NORTH CAROLINA - 90 

RUTILE - 137 

SEARCHING GRAVEL FOR DIAMONDS, BRAZIL - 78 

SECTION OF DE BEERS DIAMOND MINE, SOUTH AFRICA 84 

SHELL SHOWING IMAGES OF BUDDHA - - 213 

SPECIFIC GRAVITY BALANCE - 21 

SPHENE - 138 

TABLE CUT 46 

TETRAGONAL PRISM AND PYRAMID - 40 

TOPAZ, CRYSTAL FORMS OF 120 

TOURMALINE MINE, HADDAM, CONNECTICUT - - 115 

TOURMALINE MINE, MT. MICA, MAINE - 115 

TRAP OR STEP CUT 45 

TURQUOIS MINE, NEW MEXICO - 172 

X-RAY PHOTOGRAPH OF PASTE AND REAL DIAMONDS - 35 

WASHING GRAVEL FOR RUBIES, NORTH CAROLINA 90 

ZIRCON, CRYSTAL FORMS OF- - - - -110 



viii 



LIST OF FULL-PAGE ILLUSTRATIONS IN COLOR 

FAG* 

BIRTHSTONES - Frontispiece 

Garnet, r Amethyst, Bloodstone, Diamond, Emerald, Agate, Ruby, Sardonyx, 
Sapphire, Opal, Topaz, Turquois. 

DIAMOND AND CORUNDUM - - 66 

Diamond in matrix, Brazil; Diamond in matrix, South Africa; Carbonado, 
Bort, Sapphire Crystal, Cut Sapphire, Ruby Crystal, Cut Ruby; Spinel 
Crystal, Rubicelle; Spinel Crystal, Balas-Ruby. 

BERYL - - 98 

Golden Beryl, Siberia; Blue Beryl, Siberia; Blue Beryl, Albany, Maine; 
Aquamarine, Connecticut; Aquamarine, Ural Mountains; Emerald in matrix, 
Ural Mountains. 

TOURMALINE - - 111 

Green Tourmaline, Brazil; Green Tourmaline, Haddam, Connecticut; Tourma- 
line section, California; Red Tourmaline, Island of Elba; Red Tourmaline, 
California; Brown Tourmaline, Gouverneur, New York; Black Tourmaline, 
Finland. 

TOPAZ - - 119 

Topaz, with Mica and Feldspar, Russia; Topaz, Brazil; Topaz in Rhyolite, 
Utah; Topaz, Japan; Waterworn Topaz, Brazil. 

GARNET, CHRYSOLITE, AND EPIDOTE - 127 

Almandite Garnet, Alaska; Almandite Garnet, cut; Essonite Garnet and 
Diopside, Italy; Essonite Garnet, cut; Demantoid Garnet, Ural Mountains; 
Demantoid Garnet, cut; Cape Ruby, cut; Pyrope Garnet, Bohemia; Chryso- 
lite Crystal; Chrysolite, cut; Epidote, Knappenwand, Austria. 

QUARTZ (crystalline) - - 141 

Rutilated Quartz, Brazil; Rose Quartz, Black Hills; Smoky Quartz, Switzer- 
land; Amethyst, Virginia; Amethyst, Montana. 

AGATE - - 154 

Banded Agate, Lake Superior; Banded Agate, Brazil; Moss-agate; Clouded 
Agate. 

QUARTZ (obscurely crystalline) - 157 

Bloodstone, India; Tiger-eye, South Africa; Chrysoprase, Arizona; Agate and 
Carnelian, Lake Superior; Jasper, Germany; Ribbon Jasper, Siberia. 

OPAL - - 159 

Precious Opal in matrix, Queensland; Precious Opal, New South Wales; 
Fire Opal in matrix, Mexico; Wood Opal, Idaho; Prase Opal, Germany. 

TURQUOIS (New Mexico) - 170 

Indian Amulet; Waterworn piece; Turquois in matrix. 



PAGE 

FELDSPAR - 175 

Amazonstone, Colorado; Labradorite, Labrador; Moonstone, Norway; Sun- 
stone, Norway. 

MINOR GEMS - - 183 

Chlorastrolite, Isle Royale; Hematite, England; Thomsonite, Lake Superior; 
Thomsonite, polished, Lake Superior; Cat's-eye, Quartz, Ceylon; Variscite, 
Utah; Moldavite, Bohemia. 

SERPENTINE, SMITHSONITE, AND SATIN SPAR - 195 

Serpentine, Cornwall, England; Serpentine, polished, Cornwall, England; 
Smithsonite. Greece; Satin Spar, Italy; Thulite, Norway. 

AMBER, MALACHITE, LAPIS LAZULI, AND AZURITE - - 205 

Amber, with inclosed insect, Coast of Baltic Sea; Amber, rolled pebble, 
Coast of Baltic Sea; Malachite, Ural Mountains; Malachite, Australia; Mala- 
chite, Arizona; Malachite and Azurite, Arizona; Lapis Lazuli, Siberia. 

JADE, PEARL, AND CORAL - - 212 

Jade, variety jadeite, Burmah; Jade, variety nephrite, New Zealand; Oriental 
Pearls; Fresh -water pearl grown to shell; Precious Coral, Mediterranean 
Sea; Precious Coral, polished; Chrysoberyl, Russia. 



PREFACE 

Where do they come from? What are they made of? How can 
they be distinguished? What is their value? are questions often 
asked with regard to gems, the answers to which must be sought 
from widely scattered sources. In the hope of affording means for 
answering these questions within concise and convenient limits, the 
accompanying work has been prepared. It has been sought in it 
to avoid technical discussions; but at the same time the use of scien- 
tific terms has not been shunned, since they give increased accuracy. 
The subject as a whole has been treated from the mineralogical stand- 
point, it being believed by the writer that this affords the best basis 
for a thorough knowledge of gems. Each gem is considered under 
the mineral species to which it belongs; as, for example, ruby and 
sapphire under corundum; emerald and aquamarine under beryl, etc. 
It is probable that several gems may not at once be recognized under 
this grouping; but on the other hand, such an arrangement is likely 
to lead to a knowledge of some now little used. 

In the preparation of this book the writings of others have been 
freely drawn upon ; and in making acknowledgment of these the writer 
would refer the reader to them as means of obtaining information upon 
many points of which the scope of the present treatise has forbidden 
mention. * 

First should be mentioned the Edelstdnkunde of Max Bauer, a 
most elaborate and accurate general treatise upon gems of the present 
day. Other useful general works are Emanuel's " Diamonds and Precious 
Stones," Church's "Precious Stones," and Feuchtwanger's "A Popular 
Treatise on Gems." Kunz's "Gems and Precious Stones of North 
America" leaves nothing to be desired in the treatment of this field; 
and the annual reports in the " Mineral Resources of the United States " 
by the same indefatigable worker serve to convey from time to time the 
latest information upon gem matters. Besides the above mentioned, 
there are numerous works devoted to special provinces of the study 
of gems, which have been and may be consulted with profit. Among 
these may be mentioned Buffum's " The Tears of the Pleiades ; " Shelley's 
" Legends of Gems," King's "Antique Gems," Streeter's "The Great 



Diamonds of the World," Hamlin's " Leisure Hours among the Gems," 
Williams's "Diamond Mines of South Africa," Boutan's "Le Diamant," 
and Tassin's " Descriptive Catalogue of the Collections of Gems in the 
United States National Museum," 1902. 

To several individuals the writer is under obligations for valuable 
assistance. The Foote Mineral Company of Philadelphia kindly loaned 
numerous specimens for illustrating the colored plates. Mr. Frederick 
J. Essig, of Chicago, rendered similar aid in loaning specimens of cut 
stones and photographs, and also gave freely information regarding 
many practical points. 

To Dr. Orville A. Derby, of the Geological Survey of Brazil, Dr. J. H. 
Pratt, Mr. A. C. Lane, Dr. A. C. Hamlin, Ernest Schernikow and Prof. 
J. P. Iddings the writer is also under obligation for the loan of photo- 
graphs ; and to Dr. P. Groth, of Munich, for the loan of a half-tone plate. 

Mr. William K. Higley has given the details of preparation of the 
plates and typographical execution of the work much careful attention, 
and the writer is indebted to him for other assistance and courtesies. 

In conclusion, it is the writer's hope that this work may lead to a 
wider knowledge of gems, a more intelligent use of them and an admis- 
sion to their charmed circle of some substances now shut out because 
little known. 




NATURE OF GEMS 

Gems are minerals prized for their color, hardness, luster, and, for 
the most part, transparency. It is generally essential that a mineral 
to be a gem should excel in at least three of the above-named properties, 
although a few are superior in only two. Some minerals may, for 
example, possess desirable color and luster, but, lacking hardness, are 
little used for gem purposes, because they would become quickly marred 
when worn. Fluor-spar is an illustration of such a mineral. That 
a high degree of hardness is not essential, however, to the employment 
of a mineral as a gem is shown by the extensive use of such substances 
as pearl, amber, jet, and turquois, for gems. All of these are easily 
scratched by ordinary objects. It is to be noted, however, that they are 
not transparent substances, and that an opaque or translucent substance 
may endure, without serious injury, scratches which would be fatal 
to the beauty of a transparent gem. Hardness and color alone cannot, 
however, make a mineral suitable for gem purposes. This fact is illus- 
trated by many varieties of corundum, which have a high degree 
of hardness and good body color, but are not used for gems because 
not transparent. It is evident, therefore, that no fixed rule can 
be assigned for the use of a mineral as a gem, the favor or disfavor 
in which it is held seeming, in many instances, to be a matter 
of pure caprice. 

But, however capricious popular favor may seem to be in its estimate 
of the qualities desirable in gems, it may be set down as a fairly general 
rule, that the gems which combine the most of the qualities previously 
mentioned are those most highly prized. Thus, a red or blue diamond, 
excelling as it does all other minerals in hardness and luster, and being 
the equal of any in color and transparency, is the most valuable of gems. 
The ruby and sapphire excel in hardness, and have good color, luster, 
and transparency. They rank among the most valuable of gems. 

In speaking of minerals which have desirable gem qualities, it must 
not be supposed that this includes all occurrences of any particular 
mineral species. On the contrary, only selected portions usually have 
the desired qualities. A large part of the yield, even of diamond, 
is of no value for gem purposes, though it all finds commercial use 

i 



on account of its hardness. Quartz, one of the most abundant minerals 
of the earth's crust, though it has the qualities of hardness and luster 
suitable for a gem, can be used only in small quantity comparatively for 
gem purposes, since only few pieces have the desirable color and 
transparency. 

The selection of stones which bear the qualities above mentioned for 
purposes of possession and ornament seems to be a taste as old as the 
human race itself. In the oldest Egyptian tombs are to be found necklaces 
containing emeralds, garnets, carnelians, and other precious stones. The 
history of many gems of India dates from a period so remote as to be 
indeterminate. The desire to obtain amber led the Phoenicians to make 
some of their earliest and longest voyages. Gems were wrought into the 
earliest ritual of the Hebrews, and allusions to them are frequent 
throughout their Scriptures. The ancient Arabs were familiar with 
many of the gems used at the present day, and ascribed to them special 
qualities. The Persian turquois mines are known to have been worked 
as far back as 1300 A.D., and probably much earlier. There is frequent 
mention of gems by Greek writers, and the Romans, especially in the 
later days of the Empire, seem to have had great fondness for jewels, 
and to have sought them eagerly in their conquests. They used them 
in great variety and abundance, and carried the art of cutting and 
engraving them to a high degree of perfection. 

Moreover, gems are wrought into the history and literature of nearly 
all peoples, and furnish standards of color, hardness, luster, etc., which 
pass current the world over. Such terms as the " emerald meadow," 
"turquois sky," "adamantine hardness," etc., are derived from the use 
of gems, and have universal significance. Advances in civilization seem 
to increase rather than diminish the number of minerals used as gems, 
the number now employed being larger than ever before in the world's 
history. 

While it is true that the qualities which have been prized in gems, 
and the relative esteem in which they have been held, seem to have 
been much the same in all ages, the fashion in gems may vary from time 
to time, so that now one stone and now another may take on temporarily 
a higher value. Yet, on the whole, their worth varies little among 
different peoples and at different times. The principal exception to this 
rule is found in the valuation of jade by the Chinese, for they esteem 
this above all other precious stones. Aside from a few such exceptions, 
gems pass current in nearly all countries at about the same value. They 
hence afford to a certain extent a medium of exchange, and are often 
made objects of investment, because they are small, portable, and have 

2 



intrinsic value. It is not likely that any great excess or diminution 
of supply will occur to change the value of the leading gems, such 
as diamond, ruby, sapphire, and emerald, as they seem to be distributed 
in the earth's crust in but sparing amount. Among the less valuable 
gems, great variations in value have occurred, and may again. Thus 
the price of precious opal has steadily declined since the discovery 
of the Australian fields, although as fine gems are produced there 
as were ever known. Topaz and amethyst have suffered a similar 
decline in value, while the price of the gem known as " tiger eye " 
fell in a few years from five dollars a carat to twenty -five cents 
a pound. 

The elements entering into the chemical composition of gems are 
not as a rule themselves rare. They are chiefly silicon, aluminum, 
magnesium, and other common elements, usually combined with oxygen, 
and all abundant constituents of the earth's crust. It is thus not the 
rarity of their elements which gives gems their high value, but rather 
their peculiar properties as compounds. 

Since gems are unequal in value among themselves, many author- 
ities distinguish between gems and precious stones, and also subdi- 
vide the latter into precious and semi-precious. To the class of gems 
belong, according to such a classification, such stones as the diamond, 
ruby, sapphire, and emerald; the precious stones include amethyst, 
rock crystal, garnet, topaz, turquois, moonstone, opal, and the like; 
and the semi - precious, jasper, agate, carnelian, lapis lazuli, amazon 
stone, labradorite, etc.'" Since the different kinds and qualities grade 
into each other, insensibly however, and no sharp lines can be drawn, 
the distinction hardly seems worth making. In. tfre following pages, 
therefore, the terms gem and precious stone will be used interchange- 
ably, and will be considered to include any mineral, and even some 
substances of animal and vegetable origin, which have attained a cer- 
tain vogue for purposes of ornament. 



OCCURRENCE OF GEMS 

It was the opinion of the ancients that gems were largely confined 
in their occurrence to tropical countries. Most gems which they knew 
were so obtained, India being the chief source of them. Their wise 
men reasoned, therefore, that the warmth and light of the sun of the 
tropical zone were needed to give gems that fire and brilliancy which 
made them precious among stones. With the wider knowledge of the 
earth which has been gained in later times, however, it has become evi- 
dent that climatic conditions have little or nothing to do with the 
occurrence of gems. The greater oxidation produced by the heat of the 
sun in the tropics may add to the warmth of color of such stones as 
the carnelian and agate, but it would have a tendency to fade the 
amethyst and sapphire. A greater abundance of gems in the tropics 
may arise from more extensive decomposition of the rocks there, and 
this is undoubtedly a favorable circumstance. Moreover, glaciated coun- 
tries, such as the northeastern portion of North America, have a soil 
composed of too heterogeneous a mixture to favor the search for gems. 
So far as the underlying rock is concerned, however, there is not, so far 
as we know at present, any distribution by latitudes which favors one 
locality over another. Hence the mountain fastnesses of the Urals 
furnish gems no less than the broad valleys of India, the bleak shores 
of Labrador as well as the steaming jungles of Burmah, and the 
barren veldt of the Transvaal as well as the thickly settled valleys 
of Bohemia. 

The first discovery of gems in a region is usually made, like that 
of gold, in the beds of streams. Often it is in the search for gold that 
gems are found, as is illustrated by the fact that the discoveries of diamonds 
in Brazil, sapphires in Montana, and rubies in North Carolina were made 
in this manner. 

The frequent occurrence of gems in the beds of streams is due to the 
fact that the gem minerals are usually harder and less easily decom- 
posed than the other minerals of the rocks in which they were formed. 
Hence they remain after the mother rock has disintegrated and its con- 
stituents for the most part removed. The discovery of gems in a stream 
bed is further facilitated by the enhancing of their color when wet, 

4 



causing them to attract attention. Moreover, the flowing stream tends 
to group together minerals of the same specific gravity, thus causing 
a concentration of the gem minerals. A stream bed is therefore a good 
place to look for gems. Besides the fact that the gems are concentrated 
here, and can more easily be seen, a further advantage lies in the 
fact that they are likely to be of better quality than those found in 
the matrix, since the wear of the stream has opened and separated 
them along any little seams that may have existed, and the pieces 
left will be of uniform texture and free from imperfections. On the 
other hand, a continual reduction in size takes place from the wear 
of the stream, and larger gems will therefore be obtained by search- 
ing the mother rock. The quantity of any given gem is likely, too, 
to be limited in a stream deposit as compared with the deposit in 
place ; and just as with gold, the mother lode must eventually be sought 
if a permanent supply is desired. 

It must not be supposed, however, in speaking of stream-bed deposits, 
or " gravels," as they are usually called, that only gravels over which 
water is now flowing are meant. Beds of earlier streams will afford 
the same products and the same facilities, with the exception that 
the color of the precious stones will not be so obvious. It is evident, 
too, that in any particular gravel the quantity, size, and variety of the 
gem minerals present will depend not only on their quantity and variety 
in the original rock mass of which they formed a part, but on the 
length of time they have been exposed to wear and the rate of flow 
of the stream. 

In the so-called gem gravels, numbers of gem minerals are usually 
associated together. Thus, in those of Ceylon are to be found sapphire, 
tourmaline, zircon, garnet, spinel, iolite, and many others; and in those 
of Brazil, topaz, chrysoberyl, andalusite, and others. Quartz, garnet, 
and beryl are frequent constituents of gem gravels, as well as the 
heavier minerals ilmenite, rutile, and magnetite. The knowledge that 
garnets usually accompanied diamonds in the " wet diggings " along 
the Vaal River led to the discovery of the " dry diggings " at Faure- 
smith, in South Africa, and in other cases a knowledge of the min- 
erals usually associated with a gem has been of great aid in discover- 
ing the gem itself. This grouping together of the gem minerals arises 
from the fact that they are not only formed together in the original 
rock mass, but also that they are of about the same hardness, and 
to a certain extent, specific gravity. 

The beaches of lakes, or of the sea, also afford places for the gather- 
ing of gems by processes similar to those just described. By wave 

5 



action and currents the cliffs of the shore are continually being worn 
down, and the lighter and finer particles borne sea-ward, while those 
which are heavier, either because of higher specific gravity, or of greater 
resistance to erosion and decomposition, and hence larger, remain behind. 
A continual concentration is thus going on which in time may pro- 
duce gem deposits of some extent. The area upon which such a depo- 
sition may take place is, however, relatively narrow at any one period, 
as compared with that afforded by streams, and hence few gems are 
likely to be obtained from such sources. Labradorite and hypersthene 
are obtained from deposits of this character upon the coast of Labrador; 
chlorastrolite from the shore of Isle Royale ; and agate and thomsonite 
from beaches of Lake Superior. Hardly any other gem minerals can 
be mentioned as so obtained, with the exception of amber, which is 
gathered from the coast of the Baltic Sea. This, however, is deposited 
not through its heaviness but its lightness, it being borne upon the 
waves and tossed inland. 

Passing from the gravels in which gems are found to a consideration 
of their original rock matrices, it may be said that rocks of the kind 
known as metamorphic are more commonly than any others the home 
of the gem minerals. Metamorphic rocks are those which have been 
changed by heat and pressure, or chemical agencies, from their original 
condition. They include crystalline limestones, quartzites, mica and 
hornblende schists, gneisses, eclogites, etc. The rubies of Burmah, the 
emeralds of the Urals, the diamonds of Brazil and the garnets of the 
Alps are illustrations of gems which occur in this way. 

Next to metamorphic rocks those of an eruptive character afford 
the gem minerals in the greatest abundance. Of these the acidic 
rocks, i. e., those containing a relatively large quantity of silica, such 
as the granites, trachytes, rhyolites, and syenites, are the most prolific. 
The coarsely crystallized form of granite known as pegmatite is espe- 
cially fertile in the gem minerals. The basic eruptive rocks, i. e., those 
poor in silica, afford among gem minerals, chrysolite, some garnet, 
some corundum, vesuvianite, and a few others. They are, however, 
comparatively barren. The diamonds of South Africa occur in a rock 
seeming to be of a basic eruptive character ; but whether the diamonds 
are of primary or secondary origin is not yet known. 

Of all the great groups of rocks those of sedimentary origin furnish 
the fewest gems. Those which do occur in these are for the most 
part probably derived from older eruptive rocks. Such is believed to be 
the origin of the emeralds of Colombia, which are found in a bitumi- 
nous limestone of Cretaceous age. The opals of New South Wales, how- 

6 




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ever, occurring in sandstones and limestones of Tertiary age, doubtless 
were formed in place, and owe their deposition to the circulation 
of siliceous waters through the rocks. 

The distribution of gems through a rock or gravel matrix is not 
usually uniform. The gems more commonly occur in pockets, so called, 
the location of which seems to be governed by no law as yet dis- 
covered. Where crystallization of minerals has taken place about 
a fissure or open cavity, the minerals are more likely to be clear 
and free from inclusions than where formed in the mass of the rock 
itself. 



MINING OF GEMS 

The methods employed in the mining of gems depend obviously 
upon the occurrence of the latter. If occurring in gravels, or decom- 
posed rock areas, as is the case with the majority of gems, mining 
usually takes the form of open cuts, made either by digging numerous 
small pits, or one of extensive dimensions. The separation of the 
gems from the common pebbles accompanying them is then performed 
by some method of washing, usually hand panning combined with hand 
picking. Panning depends for its operation upon the generally high 
specific gravity of the gem minerals as compared with those of com- 
moner occurrence, and is thus similar in principle to gold panning. 
The utensil most commonly employed is a shallow pan of wood or 
metal, from 12 to 18 inches in diameter, and of a more or less coni- 
cal shape. On taking up a quantity of the gem-bearing gravel in this 
with water, and rinsing the whole with a circular motion, the lighter 
minerals fly off and the heavier concentrate toward the center. After 
the contents of the pan have in this manner been considerably reduced, 
by searching and hand picking any gems which may have gathered 
at the center can usually be readily seen and picked out. 

Of the methods of mining and separating gravels by hand digging 
and panning, the procedure of the Cingalese in exploiting the Ceylon 
gem gravels may be considered a good illustration. These methods 
are thus described by Dr. A. C. Hamlin : 

"The mining operations are generally carried on by the native 
Cingalese, who labor in the light of a pastime, and only during inter- 
vals of their agricultural employments. Some few, however, undertake 
the labor as a regular business, but they belong to a low and dissipated 
class, and do not work systematically or with regularity. Therefore, 
the gem -mining of Ceylon cannot be regarded as a fixed and per- 
manent business. 

"When an exploration has been determined upon, a small party 
of villagers set out for the promising region provided with the imple- 
ments of mining and the means of camping out. The times selected 
for the operations are after the heavy rains, which prevail in June and 
October, and the floods have subsided. The beds of rivers, or smaller 

8 







o 

CO 



c 

o 

S 



streams, are often chosen as easier of access than the plains. If the 
river-bed is selected, the first act of the explorers is to seek for the 
proper locality where the gem-bearing strata may be found. To ascer- 
tain this, the Cingalese thrust a long iron rod of ten or twelve feet 
in length into the earth, and test the nature of the sub-soil. By means 
of long practice the natives can adroitly penetrate the earth to a con- 
siderable depth; and, by the resistance to the movement of the rod, 
can detect the gem deposit of which they are in search. 

"If the indications are good, the natives proceed to build a hut 
if they are at a distance from their village, and prepare for the oper- 
ations, which often extend over many weeks. After diverting a part 
of the force of the stream so as to form a quiet pool, they proceed 
to excavate the sand and gravel within a certain area. In order 
to accomplish this they use hoes with handles fifteen or more feet in 
length. The top strata are hurriedly raked up and thrown away; 
but as the pit deepens and the gem stratum is approached, the work 
is performed with greater care. As soon as the hoes bring up frag- 
ments and boulders of white quartz, or strike thin ferruginous crust, 
every particle of the gravel drawn up is carefully preserved. The 
gravel and sand thus obtained are then placed in large baskets woven 
of split bamboo and shaped to a conical point at the bottom. The 
basket thus filled is placed in the current of water, and its contents 
washed by imparting to it a circular motion. This washing process 
is kept up until the stones, gravel, and lesser particles are cleansed. 
During this operation the gems, which are much heavier than com- 
mon stones, settle at the bottom of the basket, and are there collected 
together, so that when the superincumbent gravel is removed, the 
sapphires, garnets, zircons, etc., are easily discovered at the bottom 
and removed. This is the manner in which the wet diggings are 
carried on, and is the easiest mode of exploration; but it is by no 
means as sure, or often as profitable, as the operations in dry ground 
on the river banks or in the plains. The dry diggings are much more 
laborious, as the soil is firmer, and the gem strata must be trans- 
ported to water to be washed and sifted. These dry deposits are 
found the richest beneath the alluvial plains, which seem to have 
been in distant times shallow lakes and lagoons. 

" The gem stratum, called mellan, is always well defined, and occurs 
at a certain depth, which seems to correspond to the bottom of the 
lake at a definite period. This depth varies from two to twenty feet, 
and is perhaps even greater; but the natives rarely excavate below 
the depth of twenty feet. This peculiar formation, which is generally 



horizontal, is composed of a conglomerate of quartz gravel resting upon 
or mixed with a stiff clay, often indurated by a ferruginous oxide. In 
among this cascalho, or just below it and adhering to it, are found 
the fine pebbles and crystals of sapphire, tourmaline, garnet, zircon, 
spinel, and chrysoberyl. Under these rocks, and in peculiar hollows 
in the plastic clay, which the natives call ' elephants' footsteps,' the 
gems are found clustered together heterogeneously, and often so per- 
fect in form as to appear as though created there. At other places 
they are collected together in these pockets, in such a manner as to sug- 
gest the idea that they had been washed in by a current of water." 

An account of the methods of gem mining in Brazil, which in many 
respects are similar to those above described, will be found in the 
chapter on the Diamond in this work. Such methods may be con- 
sidered typical of the mining of gems on a small scale. Their success 
will obviously largely depend upon the skill and care of the individual 
miner. In countries where hand labor is cheap such methods can 
usually be conducted with better profit than can be afforded by the 
use of machinery. This will especially be true if the gem deposits 
are, as is often the case, scattered over a wide area and are irregular 
in quantity. 

The part of the operation of gem mining to which some form 
of machinery or apparatus can usually be most profitably applied, 
is that of washing or concentration. 

The machines employed for this purpose may vary from the crude 
"baby" of the South African Vaal River miner to the elaborate jigs 
and pulsators of the Kimberley mines. 

Most of these methods are patterned after those of gold placer min- 
ing, and depend for their success upon the same principle. 

The mining of sapphires in Montana affords an illustration of a com- 
bination of several methods of washing, which typifies what may be done 
in this manner. It is thus described by Mr. George F. Kunz in the 
Mineral Resources of the United States for 1901 : 

"The methods employed are a curious combination of those of the 
California gold-workings and the South African diamond mines. As in 
the latter, the gangue of the gems is an igneous rock, hard below 
but decomposed above, in varying degrees, to a mere earthy mass 
at the surface. From this last the gems are separated by washing 
and sluicing, much in the manner of placer gold; though, because 
of the less density of sapphires, more care is necessary, and the sluice 
boxes must be less inclined, to prevent the gems from being carried 
over the riffles. Most of the New Mine Syndicate's workings are sur- 

10 



face openings and cuts, some of the latter very extensive. Water 
is carried from Yogo Creek, ten miles distant, by a ditch and flume, 
with a parallel hydraulic pipe line; and a system of sluices extends 
all along the company's workings. 

"Where the rock is much decomposed, the hydraulic process is 
employed largely; as it becomes harder, power is necessary to break 
it up. Then the rock is thrown out in dumps and allowed to disin- 
tegrate by exposure to the weather, as with the African "hard blue." 
This process requires from a month to a year, according to the con- 
dition of the material. Sometimes a stream of water is turned on 
the dumped rock, and the process thus expedited. When sufficiently 
decomposed, this material is subjected to the same washing process 
as the material naturally disintegrated. 

"In the washing the fine earth is carried away with the water; 
all hard lumps remaining are again thrown out on a dump to decom- 
pose further; and the sapphires, after several screenings, are picked 
out by hand." 

An interesting discovery made in South Africa, in connection with 
the process of sorting diamonds by concentrating them on percussion 
tables, was that if the tables were covered with thick grease the 
diamonds, and even other precious stones, such as rubies, sapphires, 
and emeralds, would adhere to the grease and be held, while the value- 
less ingredients of the rock would pass by. The grease can be used for 
this purpose for only a few hours when it must be scraped off and a 
new coat applied. This, however, is a small disadvantage compared 
with the great gain afforded by the selective power of the " greaser," 
as it is called. 

Mining for gems by methods of tunneling, shafts, and other means 
employed in deep mine workings is rarely carried on. In the first 
place, gems do not often occur in definite veins as do the precious 
metals, being more commonly irregularly distributed in pockets through 
the rock. In the second place, little really systematic mining of gems 
is carried on. As a rule, the occupation is, or has been, a rather desul- 
tory one. A find of a few good stones leads to temporary search and 
exploration, lasting for a few years perhaps, then the work proves no 
longer profitable and is abandoned until new finds arouse * new hope 
and revive the industry. 

The element of fortune, good and bad, seems to prevail more largely 
in the mining of gems than in even that of the precious metals. In 
gem-mining, as in that for gold and silver, great labor and little reward 
go side by side with little labor and great reward. Moreover, the dis- 

11 



tribution of gems is exceedingly irregular, and their market price varies 
within wide margins, from circumstances of fashion, supply, general 
financial conditions, etc. 

Yet these contingencies might doubtless be largely overcome by 
intelligent and broad-minded management, such as has been conspicu- 
ously displayed in the conduct of the diamond mines of South Africa. 
Not only is the mining here conducted according to the most approved 
systems of modern engineering, but equal attention is paid to placing 
the gems upon the market, so that an over-supply shall not reduce the 
price. Some further account of this will be found in the chapter on 
the Diamond. 

Regarding the influence of increase of depth upon the distribution 
and quality of the gem minerals, no principles have been established 
as yet. It is known that veins of amethysts, for instance, have turned 
entirely colorless on penetrating below the surface, so that a valuable 
stone became with depth worthless. On the other hand, improvement 
in color and quality of stones below the surface, as compared with 
those above, may often be reasonably expected, since the latter are 
more exposed to disintegration and weathering, and the fading effects 
of light. 

In the mining of gems in a small way the amateur is likely to make 
the mistake of resorting to the use of too much powder or other 
explosive. While the rough work of exploration may wisely be carried 
on by means of blasting, the actual removal of the mineral from the 
matrix should usually be performed, where possible, by picks and chisels, 
in order to avoid the shattering and breaking of pieces suitable for gems, 
which often happens in blasting. Many fine gems have been lost through 
carelessness in the work of mining, and while not all losses of this kind 
can be avoided, with care and patience they can be reduced to a mini- 
mum. 



12 



COLOR OF GEMS 

The color of gems is one of the most essential features of their value. 
While certain colorless gems, such as the diamond, are highly prized, 
even the diamond would lose much of its value if it did not flash 
colored lights. So the quality of affording a permanent color probably 
leads to much of the esteem in which gems are held. The colors 
of the rose and the violet are not less pleasing than those of the ruby 
and amethyst, but the former endure but for a day while the latter can 
be handed down unimpaired from generation to generation. It was prob- 
ably to secure varieties of color that the ancients first used gems, for 
their classifications and designations of precious stones were based chiefly 
upon this property. With them almost any green stone was known as 
emerald, blue as sapphire, and red as ruby or carnelian. This fact makes it 
difficult in reading accounts of gems as given by ancient authors to know 
what mineral is meant. Distinctions of hardness and specific gravity, 
now so much in use, seem to have been ignored by them for the most 
part. With the grouping of minerals according to their chemical com- 
position, the significance of color largely disappeared as a means of 
distinction, since individual specimens of the same composition, and 
hence the same species, may vary greatly in color. Usually the quantity 
of ingredient required to produce a certain color is too small to be detected 
by chemical analysis. That the custom of distinguishing gems by their 
colors still survives, however, to a considerable extent, is evidenced by the 
fact that different names are still applied to gems of the same mineral 
when of different colors. Thus sapphire and ruby are both corundum ; 
and emerald and aquamarine are beryl. The mineral quartz appears in 
a multitude of colors, to nearly all of which different names are given. 
Hence gems of two different names may occur even in the same crystal : 
as in a piece of quartz, from one portion an amethyst may be cut and 
from another a citrine. On the other hand, different species may pre- 
sent stones of exactly the same color. Thus corundum, spinel and garnet 
all afford red stones, often nearly alike in tint ; or emerald and tourma- 
line both give green stones. Speaking from the mineralogical stand- 
point, there are few minerals and fewer gems in which color is a constant 
and essential property. Those which may be mentioned as belonging to 

13 



the latter class are pvjite, which is biass yellow, lapis lazuli, which is 
blue, and malachite, which is green. 

In a few cases differences of chemical composition are indicated by 
differences of color. This is true of garnet, the magnesium -aluminum 
varieties of which are ruby red, the calcium-aluminum varieties brownish 
red, and the calcium-chromium varieties green. So tourmaline, when 
containing an excess of iron, is black ; an excess of sodium and lithium 
is green or red, and an excess of magnesium is brown. 

Usually, however, the coloring matter is foreign to the essential com- 
position of the mineral, and of very small amount. 

This coloring ingredient is in the majority of cases organic matter of 
some sort, chiefly hydrocarbons. This has been proved in some cases by 
analysis, and in general may be assumed when the color of a stone can 
be driven out or changed by heat. The following gems quite certainly 
owe their color wholly or in part to organic matter: smoky quartz, 
amethyst, yellow topaz, golden beryl, zircon, rubellite, and amazon stone. 
The coloring ingredients of the following are chiefly inorganic : ruby, 
sapphire, spinel, and emerald. 

Next to organic matter metallic oxides are probably the most preva- 
lent coloring ingredient. These oxides may occur in scales large enough 
to be seen with the naked eye, as is true of the hematite in sunstone, or 
they may be only visible with the microscope, as the same substance can 
be seen coloring jasper and carnelian. More commonly the coloring mat- 
ter cannot be discerned as a distinct pigment. Beside oxide of iron as a 
coloring ingredient, chromium, copper and nickel oxides occur, producing 
in general green colors. Manganese oxide often gives purple or flesh colors. 

By producing some chemical change it is often possible to alter the 
color of a mineral. In the case of minerals colored by hydrocarbons, 
these changes may best be produced by heating. In this manner smoky 
quartz can be changed in color to yellow, yellow topaz to pink, and 
brown carnelian to red. 

Amethyst, hyacinth, and golden beryl lose their color entirely if heated 
any length of time, and smoky quartz may also be made colorless by 
long continued heat. Some gems change in color on heating, but regain 
it again when cooled. Thus pyrope turns darker on heating, but returns 
to its normal color on cooling. Ruby becomes colorless, but on cooling 
changes through green to its original red. 

Some colors of gems fade or change on exposure to light, a peculiarity 
which is of course considered detrimental to their value. In this manner 
the blue of turquois may change in time to green, and yellow topaz, 
chrysoprase, and rose quartz may lose their color entirely. 

14 



Some gems are of a different color by artificial as compared with day 
light. The beauty of some may thus be enhanced by artificial light and 
that of others weakened. The gem in which the most striking change is 
thus produced is chrysoberyl of the variety known as alexandrite. This is 
green by daylight, but red by artificial light. Most yellow stones appear 
nearly colorless by artificial light because the excess of yellow rays in the 
latter makes those from the stone almost invisible. For the same reason 
violet stones are likely to lose much of their color in artificial light. 
One of the points of superiority of the emerald is that it is able to retain 
its color in all lights. The color of the ruby is deepened and made more 
brilliant by artificial light, and turquois of good color has its effect 
enhanced by the same. 

LIST OF GEMS ACCORDING TO COLORS. 



Black. 
Diamond. 
Tourmaline. 
Garnet. 
Quartz. 
Jet. 

Gadolinite, Samarskite, etc. 
Blue. 
Diamond. 
Sapphire. 

Tourmaline (Indicolite.) 
Topaz. 
Beryl, 
lolite. 
Turquois. 
Lapis Lazuli. 
Brown. 
Diamond. 
Hyacinth. 
Garnet. 
Tourmaline. 
Quartz (Smoky). 
Andalusite. 
Green. 
' Diamond. 
Emerald. 

Oriental Emerald. 
Peridot. 
Chrysoberyl. 
Tourmaline. 
Dioptase. 



Green (continued). 
"Topaz. 
Garnet. 
Aquamarine. 
Euclase. 
Hiddenite. 
Malachite. 
Variscite. 
Nephrite. 
Chrysoprase. 
Heliotrope. 
Plasma. 
Pink. 
Diamond. 
Spinel. 
Ruby. 
Beryl. 

Topaz (heated). 
Tourmaline. 
Red. 

Diamond. 
Ruby. 
Spinel. 
Garnet. 
Tourmaline. 
Rhodonite. 
Fire Opal. 
Carnelian. 
Jasper. 



15 



Violet. 

Diamond. 

Amethyst. 

Sapphire. 

Spinel. 

White. 



Jade. 

Yellow. 

Diamond. 
Topaz. 
Chrysolite. 

Corundum (Oriental topaz). 

Spinel. 
Beryl. 
Amber. 
Chrysoberyl. 

Garnet. 

Hyacinth. 

Quartz (Citrine). 
Colorless. 

'Diamond. 
Zircon. 

Corundum. 
Beryl. 
"Topaz. 
Rock Crystal. 

Tourmaline. 

TtilPCOH * 

Spinel. 

Phenacite. 



LUSTER 

The luster of gems is one of their important and distinctive char- 
acters. Not only does it form one of the easiest means of distinguish- 
ing gems, but it is also one of the most reliable characters sought by 
those experts who depend for their determinations of gems on ocular 
examination alone. One familiar with the luster of quartz, as com- 
pared with that of diamond, for example, is in little danger of 
confusing the two, for the luster of one can be recognized as 
adamantine, that of the other as vitreous. The luster of a gem is pro- 
duced by the light which it reflects back to the eye, and this may 
vary in quantity and quality with the nature of the surface. Since the 
latter is largely the result of the molecular structure of the mineral, 
it follows that different species will have distinctive luster. The terms 
used to describe the different kinds of luster are derived from that 
afforded by some well-known object. Thus adamantine luster means 
the luster of the diamond; vitreous luster, the luster of broken glass; 
oily luster, the luster of oil; waxy luster, the luster of wax; resinous 
luster, the luster of resins ; pearly luster, the luster of pearl ; silky luster, 
the luster of silk ; and metallic luster, the luster of shining metals. 

Of the above kinds of luster, the vitreous is the most common among 
gems, being displayed by quartz, topaz, beryl, tourmaline, sapphire, and 
many others. The adamantine luster belongs almost exclusively to the 
diamond, although it is displayed to some extent by sphene and color- 
less zircon and is suggested by some sapphire. It is characteristic 
of minerals of a high index of refraction. Metallic luster is strictly 
possessed only by opaque minerals, and hence among gems is confined 
to pyrite and hematite. The luster of turquois is of the waxy order. 
Essonite displays a somewhat resinous luster, and chrysolite an oily 
one. Pearly luster is best seen in the pearl, but is also illustrated 
by moonstone and opal. Tiger eye and cat's eye afford examples 
of silky luster. 



16 



HARDNESS 

Tests of hardness afford one of the most useful and convenient means 
of distinguishing gems. Such tests can be easily made and are very 
reliable, the hardness of species being remarkably constant. Hardness 
should not, however, be confounded with toughness, i. e., the difficulty 
with which a mineral can be broken, since many brittle minerals have 
considerable hardness. Hardness is rather the power of resistance to 
scratching which a mineral possesses. 

It is evident that a high degree of hardness must be an important 
property of precious stones, as their polish would soon disappear if they 
were easily scratched. 

The common method of stating the hardness of a mineral is by 
referring it to its place in the scale devised by the German mineralo- 
gist Mohs. The divisions of this scale are constituted by ten rather 
common minerals, arranged according to their hardness. The scale 
is as follows : 

1. Talc. 6. Feldspar. 

2. Gypsum. 7. Quartz. 

3. Calcite. 8. Topaz. 

4. Fluorite. 9. Corundum. 

5. Apatite. 10. Diamond. 

To assist in remembering the minerals of this scale in their order, 
the following mnemonic has been devised: 

Tall Gipsy Girl Flew Up 

Talc. Gypsum. Calcite. Fluorite. Apatite. 

Fells Queer To Go Die 

Feldspar. Quartz. Topaz. Corundum. Diamond. 

The position of a mineral in this scale is determined by the minerals 
which it scratches. Thus if a mineral scratches feldspar, but is scratched 
by quartz, its hardness would be stated as 6.5. In order to test hard- 
ness, pieces of the minerals of the scale should be at hand. Fragments 
of the mineral to be tested may be grasped in the fingers and rubbed 
upon a polished surface of the minerals of the scale, or the test can 
often be more accurately made by rubbing upon the mineral of the scale a 
coarse powder of the mineral to be tested, by means of a soft pine stick. 

17 



With a little practice one may become so good a judge of the hard- 
ness of a mineral, by its behavior towards an ordinary pocket-knife, 
that the minerals of the scale below 7 may be dispensed with. Thus 
minerals of the first two degrees of hardness may be scratched with 
the finger nail ; No. 3 can be deeply scratched with a knife ; No. 4 less 
deeply and easily ; No. 5 still less so ; while No. 6 is about the hardness 
of the knife. No. 6 also scratches ordinary window glass. Upon No. 7 
a knife blade makes no impression, the steel rubbing off on the mineral. 
Steel of the hardness of a file, however, scratches quartz slightly. These 
tests are especially useful for distinguishing glass imitations from gems 
of the hardness of quartz and higher. Instead of a file it is well 
to use a point of hardened steel to avoid danger of injuring delicate 
gems. Rubbing the gem, especially if cut, with an aluminum pencil? 
is a still better means of testing hardness in the higher numbers of the 
scale, as it involves no danger of injury to the stone. Upon soft 
stones such a pencil leaves a conspicuous mark, but upon hard ones none 
whatever. Minerals above 7 in hardness are harder than a file. Corun- 
dum scratches all minerals except diamond, and diamond is the hardest 
substance known. 

Some minerals, if crystallized, are somewhat harder in one direction 
than another, the mineral cyanite being a notable illustration of this. 
Ordinarily, however, the hardness of a mineral is about the same in 
all directions. 

Table showing hardness of gem minerals : 

Diamond - - 10 Epidote 6.5 
Corundum (Ruby, Sapphire, etc.) 9 Prehnite - - 6.5 
Chrysoberyl 8.5 Pyrite - 6.5 
Topaz 8 Feldspar (Amazonstone, Moon- 
Spinel (Balas Kuby) - 8-7.75 stone, Labradorite, etc.) - 6 
Phenacite - 7.75 Turquois - 6 
Beryl (Emerald, Aquamarine, Diopside - - 6 

etc.) - 7.75 Nephrite 5.75 

Zircon (Hyacinth) - 7.5 Opal - 5.5-6.5 

Euclase 7.5 Moldavite - 5.5 

Staurolite - 7.5 Obsidian - - 5.5 

Andalusite - 7.25 Hematite - 5.5 

lolite - 7.25 Sphene - - 5.5 

Tourmaline - 7.25 Lapis Lazuli 5.5 

Garnet - - 7 Hauynite - 5.5 

Quartz (Amethyst, Rock Crystal, Cyanite 5-7 

Jasper, etc.) - 7 Dioptase - - 5 

Jadeite - - 6.75 Fluorite - 4 

Axinite 6.75 Malachite - 3.5 

Chalcedony (Agate, Carnelian, Jet - 3.5 

etc.) - 6.5 Amber - - 2.5 

Chrysolite - 6.5 Gypsum (Alabaster, Satinspar, 

Vesuvianite - - 6.5 etc.) 2 

18 



SPECIFIC GRAVITY 

The specific gravity of mineral species is also one of their funda- 
mental and constant characters, and furnishes a reliable means of dis- 
tinguishing between gems of different kinds, and of separating false 
from real stones. To be sure, a variation of composition may cause 
a variation of specific gravity in the same species; but this is usually 
within comparatively narrow limits. The different kinds of garnet, 
or of tourmaline, for example, possess specific gravities varying within 
one integer; but the varieties are usually distinguished by colors by 
which the appropriate specific gravity can be judged. One great advan- 
tage of using specific gravity as a means of identifying gems is, that the 
determination can be made without danger of injuring the stone, which 
is more than can be said of tests of hardness, fusibility, or behavior 
with acids. While specific gravity can usually be used for distinguish- 
ing between gems, as, for example, between quartz as compared with 
diamond, it cannot always be used for identifying glass, since by the 
addition of different ingredients it is possible to make glass of vary- 
ing specific gravity, and similar to that of the gem which it is sought 
to imitate. 

The specific gravity of a substance is its weight as compared with 
that of an equal volume of water. When it is stated that the specific 
gravity of topaz, for example, is 3.55, the figures simply mean that 
a given volume of topaz is 3.55 times heavier than the same volume 
of water. 

Various means may be taken to determine the specific gravity of a body, 
the most obvious and simple depending upon the fact that a body heavier 
than water loses, when weighed in that liquid, a weight equal to that 
of an equal volume of water. Hence by weighing a body first in 
air and then in water, and dividing the weight in air by the differ- 
ence between the weight in air and the weight in water, or in other 
words, by the loss of weight in water, the quotient will be the specific 
gravity. 

The following example of a determination of the specific gravity 
of a sapphire will illustrate this: 

19 



The weight in grams in air was - 12.89 

The weight in grams in water was 9.68 

Difference - 3.21 

12.89 -r- 3.21 = 4.015, the specific gravity. 

A similar quotient will be obtained whether large or small pieces 
are taken for determination, the specific gravity being totally inde- 
pendent of the actual gravity or weight. 

The determination of the specific gravity of gems or minerals becomes 
then a question simply of manipulations by which the relative weights 
of the substance in water and air can be obtained in the easiest and 
most accurate way. 

The most common and generally the most convenient way of doing 
this is by obtaining the weights of the stone in water and air directly 
by means of a delicate balance. The stone is first weighed in air 
and the weight recorded. It is then put into a holder of fine plati- 
num wire, bent into a spiral form, and suspended from the arm of the 
balance. The length of the wire is such as to allow the stone to become 
completely immersed in a vessel of water supported on a stand above the 
scale pan, but in such a manner as to allow the pan to swing free. In 
this way the weight of the stone and wire in water can be accurately 
taken. The stone is then removed, and the wire weighed suspended 
in the water as before. The weight of this is subtracted from the 
previous weight, so as to remove the weight of the wire from the 
calculation, and the remainder is the loss of weight of the stone in 
water. Dividing the weight of the stone in air by this remainder 
gives, as stated above, the specific gravity. Several precautions need 
to be taken to insure accurate results. In the first place, only dis- 
tilled water should be used, as ordinary waters have higher density. 
Again, bubbles of air often adhere to the surface of the stone, especially 
if it be rough, or if it is pervaded by cracks, which would obviously, 
if allowed to remain, lessen the weight. These can sometimes Be 
removed by dipping the stone in water several times and blowing 
the water off, or they can surely be destroyed by boiling for a few 
minutes the water in which the stone is immersed, and then allow- 
ing it to cool before the specific gravity is taken. 

Strictly speaking, the specific gravity of a body is its weight 
compared with that of water at the temperature of 4 Centigrade 
(39.2 Fahrenheit), which is the point at which the density of water 
is the greatest. Determinations at other temperatures should, therefore, 
if absolute accuracy is desired, be corrected to 4 C. In practice, however, 
the error is so trifling that it may be disregarded in all ordinary deter- 

20 



minations, especially if the temperature of the water is no higher than 
that of the ordinary living-room, say 60 F. (15.6 C.) 

In case an accurate balance cannot be obtained, a beam balance 
described by Professor Penfield, and shown in the accompanying cut, 
can be constructed by almost any one. This gives sufficiently accurate 
results for all practical purposes. It consists of a beam of wood sup- 
ported on a fine wire, or needle, at o. This must swing freely. The 
long arm, oc, is divided into inches and tenths, or into any decimal 
scale, commencing at the fulcrum, o; the short arm carries a double 
arrangement of pans, so suspended that one of them is in the air and 
the other in water. A piece of lead on the short arm serves to almost 
balance the long arm ; and, the pans being empty, the beam is brought 




Specific Gravity Balance 

to a horizontal position, marked on the upright, near c, by means of 
a rider, d. A number of counterpoises of different weights are needed. 
These may be pieces of bent wire, or bits of glass tube, with a wire 
hook fused into one end, g, some of them containing one, two, three, 
or more shot, so as to give a variety of weights. The beam being 
adjusted by means of the rider, c?, the stone or mineral which it 
is desired to test is placed in the upper pan, and a counterpoise is 
chosen, which, when placed near the end of the long arm, will bring 
it into a horizontal position. The weight, TFa, of the mineral in air, 
is given by the position of the counterpoise on the scale. The min- 
eral is next transferred to the lower pan, and the same counterpoise 
is brought nearer the fulcrum, o, until the beam becomes again hori- 
zontal, when its position gives the weight, Ww, of the mineral in water. 
Then Wa divided by Wa Ww, gives the specific gravity. 

A quick, convenient, and accurate means of separating minerals, and 
especially cut stones, according to their specific gravity, is afforded by use 
of the so-called heavy liquids. The employment of these depends upon 
the fact that a substance will float upon the top of a liquid of greater 
density than itself, will remain suspended in a liquid of exactly the 
same density as itself, and will sink to the bottom of a liquid of lower 

21 




density than itself. Now, a number of liquids are known which are 
considerably heavier than water, but whose specific gravity may be low- 
ered very gradually by the addition of water or other liquid to them. 
If a stone placed in one of these liquids remains floating it is lighter 
than the liquid. By reducing the density of the liquid a point may 
be reached where the specific gravity of the two is equal, and the 
stone will remain suspended somewhere within the liquid. Ascertain- 
ing the specific gravity of the liquid gives, therefore, that of the stone. 
Or of two stones supposed to be identical, if one sinks in the liquid 
as it is gradually diluted, long before the other, a considerable differ- 
ence of specific gravity is indicated, and the stones are doubtless 
of different species. Here, as in making determinations of specific 
gravity by weight, the relative size of the stones does not need ordi- 
narily to be taken into consideration. 

The heavy liquids principally employed for the above purposes are 
the following: A. solution of potassium mercuric iodide, known 
as Thoulet's or Sonstadt's solution, having a specific gravity of 3.15; 
methylen iodide, whose maximum specific gravity is 3.32; and silver 
thallium nitrate, which on fusing yields a liquid with a maximum 
specific gravity of 4.5-5. The first, or Thoulet's solution, is prepared 
by treating five parts by weight of mercuric iodide and four parts 
by weight of potassium iodide in a porcelain dish with a little water 
and evaporating until a crust begins to form. The solution can then 
be reduced to a desired density by adding distilled water, or can 
be brought back to the maximum specific gravity by evaporating the 
water. It can be kept indefinitely if placed in closely stopped bottles, 
especially if a few drops of mercury be added. It is poisonous. In 
using it, steel pincers or glass rods should be employed for immersing 
the stones, as the insertion of brass instruments causes a decomposition 
of the liquid, and a deposition of mercury upon the metal. 

While the Thoulet solution is the cheapest and easiest of the heavy 
liquids to manipulate, its rather low density prevents its use for gems 
having a specific gravity much over 3, and hence some of the other 
liquids are often preferred. Methylen iodide is recommended by Bauer 
as best suited for the general purposes of the student of gems. This 
has, as stated, a maximum density of 3.32; but by saturating with 
iodine and iodoform a density of 3.6 may be obtained. The useful- 
ness of the latter mixture is somewhat impaired, however, by its very 
dark color. 

The dilution of methylen iodide is performed by means of benzol 
rather than by water. Bauer recommends having for use four differ- 

22 



ent strengths of the liquid, which may be preserved in four labeled 
bottles side by side. By dropping the stone whose specific gravity 
it is desired to test, into different bottles successively, its specific gravity 
can be learned within narrow limits. It is recommended to place in the 
first bottle a solution of methylen iodide saturated with iodine and 
iodoform. Its specific gravity would be 3.6. The second bottle 
should contain pure methylen iodide, marking a specific gravity 
of 3.3. The third bottle may contain the same, diluted until its specific 
gravity becomes 3.0, and the fourth the liquid reduced to a specific 
gravity of 2.65, which is that of quartz. Topaz and diamond would 
then float upon the first liquid, but sink in the second. Hyacinth, 
ruby, and sapphire, would sink in all. Beryl, emerald, etc., would 
float upon the first three, but sink in the last, and so on. 

The bottles containing the solutions should be kept tightly stoppered, 
as any evaporation affects the density of the liquid. Methylen iodide 
is a somewhat expensive chemical, costing, as it does, $1.25 an ounce; 
but when a supply is once obtained it will last almost indefinitely. 

Instead of having solutions of different densities at hand, some pre- 
fer to have ready for use fragments of minerals of different densities 
arranged in series. These are called indicators, and are used by placing 
one or more in the liquid with the stone whose specific gravity is desired, 
and diluting until the indicator sinks or rises at the same time with 
the unknown mineral. The unknown mineral must then be of the 
same specific gravity as the indicator. 

For minerals with a specific gravity above 3.6, the only heavy liquid 
available is silver thallium nitrate. This, as previously stated, fuses 
to a clear liquid having a density of 4.5 to 5. The temperature required 
for fusion is about 75 Centigrade (167 F.), and the work can be con- 
veniently done by heating the salt in a beaker upon a water bath. 
The dilution can be performed by adding hot water. The necessity 
of working always with hot liquids is of course a drawback to the 
use of this substance, and it is also a costly chemical. In other 
respects it answers well the purposes of a heavy liquid. It should 
be noted in the use of all the heavy liquids that the addition of a very 
small amount of water, or other diluting liquid, is sufficient to consid- 
erably reduce the specific gravity. Hence, the addition of the diluting 
liquid should be made very slowly and carefully, with frequent stirring, 
and a constant watch on the position of the stone that is being tested. 
For the purpose of determining exactly the specific gravity of the 
liquid at any point, some form of balance is usually employed, that 
known as Westphal's giving quick and accurate results. It is, however, 

23 



a somewhat expensive piece of apparatus, and any one not wishing 
to incur such an outlay may obtain results nearly as good with the 
beam balance previously described. In its use for this purpose a sinker 
in the shape of a cylindrical bulb is suspended from a position marked 
by a notch near the end of the long arm. By putting shot in the 
pans and using the rider d, the beam is brought to a horizontal 
position with the sinker in air. The sinker is then immersed in 
the heavy solution, and a weight is selected, which, when placed 
near the end of the beam will bring the latter to a horizontal position. 
The position of this weight gives relatively the weight of the heavy 
solution displaced by the sinker. After washing, the sinker is immersed 
in water, and the same weight is placed nearer the fulcrum until the 
beam becomes horizontal. The position of this weight gives relatively 
the weight of the water displaced by the sinker. The larger weight 
divided by the smaller gives the desired specific gravity. 

By employing proper formulae, weights of bodies may be found if 
their specific gravities be known, or the specific gravity of one, if its 
weight and the weight and specific gravity of another be known. 

Thus if a diamond is set in a gold ring, it is often desirable to know 
the weight of the diamond, or its specific gravity, or the specific gravity, 
and hence the fineness, of the gold of which the ring is composed, with- 
out removing the stone. Each of these values, and even others, can be 
found by employing the following formulae. These are derived from 
two equations in which A represents the weight of the stone, a its specific* 
gravity; B the weight of the gold, and b its specific gravity; and C the 
combined weight of the ring and stone, and c their specific gravity. 

Then A + B = C 

A^B C 

and _+__= 

a b c 
Whence we obtain for A, 

A = C ( b c ) a 
(b a) c 

for a, Abe 



C(b c) + Ac 

for b, i _ B a c 

= C(a c) + Bc 

and expressions for other factors if desired. 



TABLE SHOWING SPECIFIC GRAVITY OF GEM MINERALS 



Zircon (Hyacinth) 

Almandine Garnet - 

Ruby - 

Sapphire 

Cape Ruby (Garnet) - 

Demantoid (Garnet) 

Staurolite - 

Pyrope (Garnet) 

Chrysoberyl 

Cyanite - 

Cinnamon Stone (Garnet) 

Spinel (Balas Ruby) 

Topaz 

Diamond 

Epidote 

Vesuvianite 

Sphene 

Chrysolite 

Jadeite 

Axinite - 

Diopside 

Dioptase 

Andalusite 

Apatite - 

Hiddenite - 



4.60-4.70 


Green and Blue Tourmaline - 3.11-3.16 


4.11-4.23 


Euclase - 


3.05 


4.08 


Fluorspar 


-, 3.02-3.19 


4.06 


Nephrite 


3.00 


3.86 


Phenacite 


- 2.98-3.00 


3.83 


Red and Colorless Tourmaline 2.94-3.08 


3.73-3.74 


Turquois 


2.60-2.80 


3.69-3.78 


Labradorite 


- 2.70 


3.68-3.78 


Beryl 


2.68-2.75 


3.60-3.70 


Emerald 


- 2.67 


3.60-3.65 


Rock Crystal ^ 




3.60-3.63 


Smoky Quartz 




3.50-3.56 


Amethyst 


. - 2.65-2.66 


3.50-3.52 


Jasper 




3.35-3.50 


Chrysoprase 




3.35-3.45 


lolite 


- 2.60-2.65 


3.35-3.45 


Chalcedony j 


2.60 


3.33-3.37 


Agate i 




3.30 


Obsidian - 


- 2.50-2.60 


3.29-3.30 


Moonstone (Adular) 2.55 


3.20-3.30 


Lapis lazuli 


- 2.40 


3.29 


Moldavite 


2.36 


3.17-3.19 


Opal - 


- 2.19-2.20 


3.16-3.22 


Jet 


1.35 


3.15-3.20 


Amber 


- 1.00-1.11 



25 



OPTICAL QUALITIES 

Since the pleasing qualities of gems depend largely upon their effects 
upon light, some general statements as to the properties of light, and the 
manner in which it is affected in passing through gems, will be desirable. 
The generally accepted theory of the transmission of light is that it 
moves in a straight line without change of direction in one and the same 
homogeneous medium, as vibrations of particles of the luminiferous 
ether which may be called light waves, and which take place at right 
angles to the direction of transmission. In some media the velocity 
of transmission of light is independent of the direction in which it is 
propagated. Such media are called isotropic, and include among gems, 
opal, diamond, spinel, and garnet. In other media the velocity of trans- 
mission of light varies in different directions. Such media are said to 
be anisotropic. Most gems belong to this class of bodies. The velocity 
of transmission of light through different media differs, but has an 
absolute value for one and the same substance. 

Media in which light is transmitted at a high velocity are said to 
be optically rare, those in which it is transmitted at a low velocity are 
said to be optically dense. In passing from one medium to another of 
different density, as for instance from air into water, light undergoes a 
change in its rate of transmission and a change of direction. This change 
constitutes the phenomenon of refraction, the most familiar illustration 
of which is seen in the apparent bending of a stick 
partly immersed in water. If the amount of this 
change of direction be studied, it will be found to 
have a definite angular value which is constant for the 
same substance. Thus, if in the accompanying figure 
a ray of light passing through the air from L be sup- 
posed to fall upon the surface of water at A, it will be 
refracted in the direction A K. The angle L A B is 
Diagram illustrating ca u e( j the angle of incidence, and K A C the angle of 

refraction of lignt 

refraction, B C being a perpendicular to the water's 
surface. If from A as a center a circle B C be described, and from the 
points ra and p where this circle cuts the incident and refracted rays 
the lines ra n and p q be drawn perpendicular to B C, then will 

26 




m n be the sine of the angle of incidence, and p q the sine of the angle 
of refraction. Now, it is found that whatever the direction of the 
incident ray, that of the corresponding refracted ray is so conditioned 
that the quotient of the sine of the angle of refraction into the sine 
of the angle of incidence is a constant quantity for the same media. 
This quotient is called the index of refraction. It is to be found in the 
instance above quoted by dividing m n by p q. The greater the refractive 
power of the substance the smaller will be the value of p q, and the larger 
the quotient, which is the index of refraction. Hence substances with 
a high refractive power have a large index of refraction, as diamond, 
whose index of refraction is 2.42. That of water is only 1.336. Garnet 
has an index of refraction varying from 1.75 to 1.81 in different varie- 
ties. Zircon is another gem mineral which possesses a high index of 
of refraction, this being 1.96. Diamond is the most highly refractive 
of the gems, however. 

It is to be noted that the amount of refraction of the different com- 
ponent colors of a ray of white light is a variable quantity, and hence in 
every refraction the ray is broken up in a way similar to that in which 
it is separated into the colors of the spectrum in passing through a 
prism. This variation in the refraction of the different colors is called 
dispersion. The red waves, for example, suffer less change of velocity 
than the blue, and hence the refractive index for a given substance is 
greater for blue than for red light. Substances differ in the degree of 
refraction which the waves of the different colors suffer in passing through 
them, and hence in the degree to which they separate the component 
colors ; that is, they differ in what is called dispersive power. Diamond 
has high dispersive power, its index of refraction for red light being 
2.407+, and for violet light 2.464+, while spinel, which has only an 
average dispersive power, has a difference in indices between red and 
violet light only between 1.712-f- for red, and 1.726 for violet. 

A particular phase of the relations of the incident and refracted rays 
should be noted here, as it has much to do with increasing the brilliancy 
of gems. 

When a ray of light attempts to pass from a denser into a rarer 
medium there are conditions under which the angle of refraction cannot 
be greater than the angle of incidence. Under such circumstances the 
ray cannot emerge from the denser medium, but will be wholly reflected 
at the point of incidence. Thus, in the following figure, if the lumin- 
ous rays from A passing out of the water be traced it will be found that 
since the angle of refraction increases more rapidly than that of incidence 
certain rays cannot emerge at all, but are refracted or reflected back into 

27 




Diagram showing paths of 
rays passing from a dense into 
a rare medium 



the water. This is familiarly illustrated in looking into a glass of water 
held above the eye, by the fact that the surface of the water appears 
to be silvered and opaque, owing to the total reflection of a large num- 
ber of rays. The path of the rays is more 
fully illustrated in the next figure, showing a 
ray of light, L A, passing out of the water by 
refraction in the direction A R. If the angle 
of incidence, C A L, be gradually increased, 
the angle of refraction will also increase, but 
more rapidly than the angle of incidence until 
it becomes equal to 90, when the ray will 
graze the surface of the water at A M. If 
the source of light be still further removed as 
to Z, the ray can no longer pass out, but is reflected to r. The inci- 
dent angle at which internal reflection will thus take the place of refrac- 
tion is called for every substance the critical or limiting angle, and is 
a constant angle for each different substance. For water (with refer- 
ence to air) this angle is 4835', for flint glass 3736', and for diamond 
23 53 ' . Substances with a low critical angle or in other words, highly 
refracting substances will appear more brilliant than those of low 
refractive power, because the amount of light striking upon them becomes 
concentrated into a smaller part of the surface. 
This can be proved by a mathematical calculation, 
but it is too abstruse for these pages. The fact, 
however, can be made evident by observation. A 
large amount of total reflection, such as is afforded 
by substances of high refractive power, has, 
moreover, the advantage of returning light to 
the eye which would otherwise pass through the 
stone and be lost. How this is done is shown by 
the following figure after Bauer, representing 
the path of a ray of light in a diamond cut 
as a brilliant. The ray enters in the direction a b and being totally 
reflected from the various points of the interior comes back in some- 
what the general direction m g in which it started. It does not come 
back, however, as a single ray, but is broken up by the refraction into 
its differently colored components. Hence the particular ray which 
reaches the eye may be red or blue, or some other color. To this 
refractive power, therefore, the diamond owes the property of flashing 
colored lights which gives it so much of its beauty and attractiveness. 
When refraction, or reflection, of a ray of light takes place, the ray 

28 




Diagram illustrating re- 
fraction of light at different 
angles 




undergoes another change, known as polarization. Polarized light is 
that having vibrations taking place in a single plane instead of in an 
innumerable number of planes, as is the case with ordinary light. A 
partial polarization of light occurs with every 
refraction and reflection, but it is not complete. By 
means of proper appliances a perfect polarization can 
be obtained. Polarized light is of great advantage in 
the optical study of gems, since it affords a ray the 
plane of whose vibrations can be accurately ascer- 
tained. Light may be polarized by causing it to be 

reflected from two mirrors, and an instrument some- 
Path of a ray of light 

times used for obtaining polarized light is constructed in a diamond cut as a 

.1 . . . i ' rrn i 17 brilliant. After Bauer 

upon this principle. Ine most commonly used polar- 
izer, however, is the so-called Nicol prism, an appliance constructed from 
two pieces of Iceland spar, in a manner which can best be understood 
when the subject of double refraction has first been considered. 

Light propagated in the anisotropic media previously mentioned, 
instead of advancing in all directions with the same velocity, as is the 
case with isotropic media, advances in different directions with different 
velocities. These directions resolve themselves into two, corresponding 
to the directions of the greatest and least elasticity in the medium. 
A ray of light entering such a medium is therefore broken up 
into two rays, which have distinct properties and move independently 
of each other. The refraction of the ray instead of being single, 
as is the case with isotropic media, is double, and such media are 
hence said to be doubly refracting. To this class belong most gems, 
since substances crystallizing in any of the systems except the isometric, 
unless they are amorphous, possess this property. The most familiar 
illustration of the double refraction of light is seen when an object such 
as a black cross upon paper or a line of ordinary print is looked at 
through a piece of Iceland spar. The characters when thus seen appear 
double, and of only about half their normal intensity, except where two 
images may come together. The phenomenon is more evident in Iceland 
spar than in other minerals because the two rays are more widely separ- 
ated in this substance than is usually the case, but the breaking up into 
two rays and the separation take place in many other minerals neverthe- 
less. The two rays are known for distinction as the ordinary and extraor- 
dinary rays. Each is polarized, so that it is evident that if some means 
can be found of eliminating one of them, the other may be made to 
furnish a convenient source of polarized light. This is what is done in 
the construction of the Nicol prism, it being made of two pieces of 

29 




IE 

Construc- 
tion of the 
Nicol prism 



Iceland spar cut in definite directions, and cemented together by Canada 
balsam. The construction is shown in the accompanying figure. The 
parallelogram represents the outline of the prism, and the line running 
nearly as a diagonal shows where the two parts are joined 
together. 

A ray of light, m n, falling upon the prism is at once 
refracted into two rays, n and n E. The ray n upon 
reaching the layer of balsam is totally reflected, and passes 
out at Oj, where it disappears. The ray n E, however, 
passes through, and reaches the eye as a ray of polarized 
light, having its vibrations in a single plane. If now this 
ray fall upon another Nicol prism standing in the same 
vertical direction, and similarly oriented, it can pass 
through without sensible loss or change, and so on through 
a large number if necessary. If, however, the second prism 
while maintaining the same vertical direction be rotated 90 
about its vertical axis, the ray upon reaching it will follow 
the path n instead of n E, since the ordinary and extraordinary rays 
are situated at right angles to each other. It will therefore be absorbed 
and lost, and no light will reach the eye. 

If a plate of a singly refracting substance be interposed between the 
two prisms, no change will occur in the above-named phenomena ; but if 
a doubly refracting mineral be inserted instead, the field of view will 
light up, except in four positions, 90 from each other. It is obvious 
that the passage of light through the second prism in the latter case 
comes from the fact that the polarized light from the first prism is 
broken up into two rays in traversing the doubly refracting plate, one of 
which is traveling in such a direction as will permit it to pass through 
the second prism. These differences of behavior of doubly refracting 
as compared with singly refracting bodies afford a convenient and ac- 
curate means of distinguishing gems, for the tests can be made with- 
out danger of injury to the stones. The essential features of an 
apparatus for the purpose are two Nicol prisms set in a frame one 
above the other, with a stage, preferably a revolving one, between. 
One of the prisms must be capable of being rotated about its axis. 
The lower prism is usually called the polarizer; the upper one the 
analyzer. Having turned the prisms with reference to each other so 
that the field of view is dark, when a singly refracting substance, such 
as diamond, spinel, garnet, or glass, is inserted between the two, no light- 
ing up of the field can be observed except such as may come from a 
reflection from facets of the object. This reflection should not be con- 

30 



founded with an appearance of transmitted light. A doubly refracting 
stone will, however, when inserted, be lighted internally, showing much 
the same color, though less strongly, as that which it possesses in ordinary 
light. On revolving the stone by means of the movable stage, it will 
be seen to become dark four times during a complete revolution, the 
intervals of darkness occurring every 90 from each other. 

Thus quartz may be distinguished from diamond, quartz from glass, 
zircon from diamond, or any doubly refracting stone from a glass imita- 
tion, and so on. Diamond cannot be distinguished from glass, nor from 
spinel, by this test, since all are singly refracting. Other tests, such as 
those of specific gravity and hardness, will, however, be sufficient to 
distinguish in such cases. It is of course true that stones cut from 
doubly refracting minerals in certain directions appear like singly 
refracting ones, and a possible error may be made on this account. In 
practice, however, the likelihood of meeting with stones cut in just such 
directions is very small, and may be ignored. An apparatus constructed 
for the determination of gems by the above methods is illustrated in the 
following figure (p. 32).* Here the polarization of the light below the 
stone is accomplished by means of two mirrors, and thus the cost of 
one Nicol prism is saved. The stone is placed upon the stage d. The 
light, polarized by the mirrors, passes through the stone into the tube 
above containing the analyzer, and through this to the eye. By rotat- 
ing the tube in the holder /, the distinction in appearance between 
singly and doubly refracting minerals can be readily seen. The ordi- 
nary petrographical microscope also affords the necessary appliances 
for determinations of this kind. Tourmaline tongs furnish another com- 
bination of a polarizer and analyzer, but they allow too little light to 
pass through to be of practical value for determining minerals. 

Doubly refracting substances have another feature in distinction from 
singly refracting ones, in the fact that the rays passing through them are 
differently absorbed, and hence give different colors in several directions, 
while singly refracting substances are normally of the same color in all di- 
rections. In the degree to which they exhibit this property of dichroism, 
or pleochroism, as it is called, minerals vary. lolite is one of the most 
strongly dichroic minerals, and can plainly be seen to be dark blue in one 
direction and clove-brown in another. Transparent zircon is often pinkish 
brown in color when looked at it in the direction of the vertical axis, and 
asparagus-green when seen laterally. Tourmaline is often nearly opaque 
when looked at in the direction of the vertical axis, but transparent when 

* This instrument can be obtained of R. Fuess, Steglitz bei Berlin, Germany, at a cost of 
eighteen to twenty dollars. 

31 



seen laterally. In other doubly refracting minerals the dichroism may 
not be sufficiently apparent to be positively observed with the naked eye. 
The detection of the dichroic character can usually be made, however, 
with the aid of the little instrument known as the dichroscope.* This 
consists of an oblong rhombohedron of Iceland spar with a glass prism 




Instrument for examining gems in polarized light 

of 18 cemented to each extremity, or with the end faces ground and 
polished so as to be perpendicular to the length of the prism. It is 
placed in a metallic cylindrical case, and is provided with a convex lens 
at one end, and a square hole at the other, the focal length of the lens 
being such as to show a distinct image of the square opening. On look- 

* This instrument can be obtained of Negretti & Zambra, 38 Holborn Viaduct, London, 
at a cost of about five dollars. 



ing through the dichroscope the square hole appears double, since both 
the ordinary and extraordinary ray give an image. If a piece of mineral 
or cut stone is held in front of it, two images of this are likewise seen. 
These images are of different colors if the mineral is a doubly refracting 
one, since the two rays are differently absorbed in passing through such 
a mineral. The two images being side by side even slight differences 
of color can be perceived. The following are some of the twin colors 
exhibited by the more important gems when viewed in this manner, as 
stated by Church : 

NAME OF STONE , TWIN COLORS s 

Sapphire (blue), Greenish straw, Blue. 

Euby (red), Aurora-red, Carmine-red. 

Tourmaline (red), Salmon, Rose-pink. 

" (brownish red), Umber-brown, Columbine-red. 

" (brown), Orange-brown, Greenish yellow. 

" (green), Pistachio-green, Bluish green. 

" (blue), Greenish gray, Indigo-blue. 

Topaz (sherry), Straw-yellow, Eose-pink. 

Peridot (pistachio), Brown-yellow, Sea-green. 

Aquamarine (sea-green), Straw-white, Gray-blue. 

Beryl (pale blue), Sea-green, Azure. 

Chrysoberyl (yellow), Golden brown, Greenish yellow, 

lolite, Pale buff, Indigo-blue. 

Amethyst, Keddish purple, Bluish purple. 

The dichroscope thus affords a convenient and accurate means of 
distinguishing gems. Any one of those in the above list, for example, 
could be distinguished from a glass imitation by the fact that any glass 
substitute would give two images of exactly the same color, instead of 
different colors, as would the genuine stone. Such gems as diamond, 
garnet, and spinel cannot, however, be distinguished from glass or each 
other in this manner, since they give similarly colored images. 



33 



ELECTRICAL PROPERTIES, PHOSPHOR- 
ESCENCE, AND FLUORESCENCE 

All gems when rubbed upon cloth become, like glass, positively 
electrified. Gems differ, however, in the length of time during which 
they will retain an electrical charge. Thus tourmaline and topaz remain 
electric under favorable conditions for several hours ; but diamond loses 
its electricity within half an hour. The electrical peculiarities of differ- 
ent species were at one time used quite extensively for identifying 
them; but owing to different behavior under different atmospheric 
conditions little use is now made of such tests. Besides developing 
electricity by friction some gems become electric upon heating. Such 
are said to be pyro-electric. To test a stone, or rough piece of mineral 
for this property, it can conveniently be held in forceps and heated 
gently in a colorless flame, such as that of a Bunsen burner or alcohol 
lamp. The amount of heating should not be much over 100 C. On 
withdrawing the stone, it will, as it cools, if pyro-electric, attract bits 
of tissue paper or straws. Tourmaline is perhaps the most strongly 
pyro-electric of the minerals used as gems, and the property affords 
a means for identifying it. Topaz is another gem mineral which 
usually exhibits this property. Some topaz also becomes electric when 
subjected to simple pressure. This is said to be true of some crystals 
of Brazilian topaz if they are pressed between the ringers in the direc- 
tion of the vertical axis. Electricity developed in this way is known 
as piezo-electricity. 

Simple tests for all these kinds of electricity consist in the attrac- 
tion of light objects, such as bits of tissue paper, cat hairs, pith balls 
suspended by silk threads, etc. They are best made when the atmos- 
phere is dry, the winter season being especially favorable. 

Some gems have the property of emitting light after heating, exposure 
to light, or an electrical discharge. This property is known as phosphor- 
escence, since the glow, although it is often of different colors, resembles 
that emitted by phosphorus. The diamond is a mineral which exhibits 
this property, some of its gems after exposure to sunlight for a short 
time emitting a glow which can be plainly seen in a dark room. This 
is often stated to be a property of all diamond, but this is incorrect, 

34 



some stones exhibiting no change whatever after exposure to sunlight. 
Phosphorescence may also be called out in the diamond by rubbing it, 
especially across the fibers of a piece of wood. Among all minerals 
phosphorescence is best exhibited by fluorite, nearly all specimens 
of which will, when gently heated, emit a visible light. The color 
of the light varies with different varieties, and is usually not the same 
as the natural color of the mineral. The tints exhibited are usually 
greenish, bluish, or purplish. On increased heating the phosphorescence 
disappears, and cannot be restored again except by passing an electric 
discharge through the mineral, whereupon the lost power is usually 
regained. The same is true of diamond. It is generally supposed 
that the phosphorescence of minerals results from the presence within 
them of particles of organic matter of the nature of hydrocarbons, 
which are aroused to a certain activity on heating. Of the exact 
nature of the phenomenon, however, little further is known. 

Closely allied to phosphorescence is fluorescence, which, in a strict 
sense, is the emission of light within a substance while it is being 
exposed to light, or in some cases to an electrical discharge from 
a vacuum tube. Fluorite is again the mineral which best exhibits 
this property, a beam of white light passing through a colorless cube 
of it producing a delicate violet color. The diamond, ruby, and other 
gems are stated by Dana to give forth 
a brilliant fluorescence when exposed to an 
electrical discharge from the negative pole 
of a vacuum tube. Fluorescence is also pro- 
duced in the diamond by radio-active sub- 
stances; that is, by radium, or substances 
possessing its activity. In this respect dia- 
mond differs from such gem minerals as 
ruby, emerald, topaz, etc., and from glass, 
in none of which do the radium rays excite 

much activity. X-ray photograph of paste and 

The behavior of gems toward X-rays or ^idn taring a? *&, to 




n rays Varies with different species, opaque; the real diamonds, in the 
, , j. , . . . . , . ring at the right, transparent. 

and artords a means ot distinguishing them. 

Thus diamond is quite transparent to the rays, while glass is opaque. 
Accordingly, in an X-ray photograph, such as is shown in the accom- 
panying figure, of two rings, the one set with diamonds, the other with 
paste, the diamond can readily be known by its transparency. 

The behavior of others of the gem minerals in relation to the X-rays 
is further shown in the following table : 

35 



COMPLETELY TRANSPARENT. 

Amber. 

Jet. 

Diamond. 

STRONGLY TRANSPARENT. 

Corundum. 

TRANSPARENT. 

Opal. 

Andalusite. 
Cyanite. 
Chrysoberyl. 

SEMI-TRANSPARENT. 

Quartz. 
Labradorite. 
Adular. 
Topaz. 



SLIGHTLY TRANSPARENT. 

Spinel. 

Essonite (Garnet). 

Fluorite. 

ALMOST OPAQUE. 

Gypsum. 
Turquois. 
Tourmaline. 
Calcite. 

OPAQUE. 

Almandite (Garnet). 

Beryl. 

Epidote. 

Rutile. 

Hematite. 

Pyrite. 

Zircon. 



36 



CRYSTAL FORM 

The crystal form of minerals serves as an important means of identi- 
fying them, since crystals of each species, in any system, except the 
isometric, have forms peculiar to that species. The actual determi- 
nation of species in this way, however, requires a careful measurement 
of angles, trigonometrical calculations, and a knowledge of crystal forms 
obtained through a study of that branch of mineralogy known as crystal- 
lography. The mastery of this subject is usually beyond the purpose 
of the student of gems, nor is it essential. A more practical need 




Distortion of a cubical crystal by variations in growth 

for him is to obtain a certain empirical familiarity with the common 
external forms of the crystals of each species, together with a knowl- 
edge of the ways in which distortion may occur, preventing recognition 
of the regular forms. 

In the following pages, under most of the species, are given illus- 
trations of the common forms of those species, which one soon learns 
to associate with that particular mineral. 

In all comparisons of figures with actual crystals, however, it must 
be remembered that crystals in nature rarely present the complete, 
symmetrical form which the geometrical figure would indicate. While 
the angles between the faces remain practically always the same, there 
occur much distortion and imperfect growth of crystals which may 
be quite misleading. Certain faces may be so much developed that 
others which would normally be present, do not appear at all; and 
again, the attachment of the crystal to its matrix often prevents develop- 
ment of the complete form, or obscures its presence. 

Thus in the above figure the cube, which would be the normal crystal 
form, may become by continued growth in the vertical direction elon- 

37 



gated like the form shown at its right, or by growth laterally the tabular 
form shown may be produced. 

So again, the quartz crystals represented below are all made up of 
the same faces and have the same interfacial angles, yet they would seem 




+c 



-fa 



. o 



Forms of quartz crystals produced by distortion 

at first sight to have no similarity of form. One can soon become famil- 
iar with these variations, however, and by making due allowance for 
them learn to recognize crystal forms quickly and accurately. 

In addition to an empirical familiarity with the forms of crystals, 
some knowledge of the general groups of crys- 
tals is desirable, since there are thus expressed 
relations which characterize not only the ex- 
ternal form, but internal structure. 

The forms into which a mineral, or any 
substance of definite chemical composition, 
may crystallize, are divided into six systems. 
These are known as the isometric, tetragonal, 
hexagonal, orthorhombic, monoclinic, and tri- 
clinic systems. By some a seventh, called the 
rhombohedral system, is added, though here it 
is considered a subdivision of the hexagonal. 
In the discrimination of crystal forms, the 
relations of the planes can best be expressed 
by referring them to a series of three or more 
imaginary axes within the crystal. One of 
these, known as a, is supposed to run from 
front to back ; another, known as 6, from Crystal Axes 

right to left ; and the third, known as c, vertically The latter is known 
as the vertical axis, and the two former are designated as lateral axes. 
In the hexagonal system, the existence of three lateral axes is assumed. 

The differences between the six systems can be stated in terms of 
these axes as follows: 




In the isometric system the axes are of equal length, and at right 
angles to each other. In the tetragonal system one axis, usually taken 
as the vertical, is longer or shorter than the other two, which are equal 
in length. The axes are all at right angles to each other, however. In 
the hexagonal system one axis, usually taken as the vertical, is longer 
or shorter than the lateral axes and at right angles to them. The 
lateral axes are three in number, of equal length, and meet at angles 
of 60. In the orthorhombic system the three axes are of unequal 
length, but meet at right angles. In the monoclinic system the three 
axes are of unequal length. Two of them meet at right angles, while 
the third is inclined. In the triclinic system the axes 
are of unequal length, and meet at unequal angles. 

The axial relations above class- 
ified are paralleled in the symmetry, 
both external 
and internal, of 






Cube 
Crystals. Thus Octahedron 

crystals of the 

isometric system are the most highly Dodec ^edron 
symmetrical, and those of the tri- 
clinic system the least so. By symmetry is here Trapezohedron 
understood the relation which an object has to its 
reflection in a mirror ; and another way of stating the previous obser- 
vation would be to say that an isometric crystal can be held before 
a mirror in more positions in which the crystal and its reflection 
present the same appearance, than one of any other system, while with 
a triclinic crystal no such position can be found. Besides the division 
into six systems, each system is itself subdivided into groups of varying 
kinds of symmetry. There are thirty-two of these groups, characterized 
by a particular kind of symmetry, and a substance crystallizing in a 
certain group will invariably show that symmetry. 

A few simple forms peculiar to different systems may be mentioned 
here, since the terms will be often employed in the text. Four common 
forms, exhibited by minerals crystallizing in the isometric system, are 
the cube, octahedron, dodecahedron, and trapezohedron. The cube is 
a solid bounded by six similar faces, each parallel to two of the axes. 
Each face is a square, and the interfacial angles are all 90. Crystals 
of this form are exhibited by pyrite, fluorspar, and rarely by diamond. 
The octahedron is bounded by eight similar faces, meeting the axes 

39 




Tetragonal prism and 
pyramid 



at equal distances. Each face is an equilateral triangle. Diamond and 
spinel are gem minerals which often exhibit crystals of this form. 
The dodecahedron is bounded by twelve faces, each of which meets 
two of the axes at equal distances, and is parallel to a third axis. 
Each face is a rhomb. Garnet quite commonly crystallizes in this form, 
as well as in that of the next type, the trapezo- 
hedron. The trapezohedron is bounded by 
twenty-four faces, each of which is a trapezium. 
Each face intersects one axis at the unit length, 
and meets the other two axes at distances 
greater than unity. The form bears some rela- 
tion in appearance to the octahedron, if it be 
imagined that three faces of the trapezohedron 
occupy the place of one face of the octahedron. 
In other systems than the isometric, the 
simplest and in general the most commonly occurring forms are prisms 
and pyramids. Prisms are forms whose faces are parallel to the vertical 
axis, while they meet the lateral ones; pyramids are forms whose 
planes meet all three of the axes. 

In the hexagonal system prismatic and pyramidal faces occur in 
multiples of three, while in the tetragonal, orthorhombic, etc., systems, 
they occur in multiples of two. Thus a crystal of zircon 
may be distinguished from one of quartz, for example, by 
the fact that on the former four or eight similar pris- 
matic faces may be counted, on the latter, three or six. 

Substances vary considerably in their tendency to form 
distinct crystals, or even to crystallize. Quartz, in the 
form of rock crystal and amethyst, is generally found in 
distinct crystals, while agate, chalcedony, etc., although 
crystalline, and of the same composition, never form 
separate crystals. . Such substances as opal, turquois, 
obsidian, and obviously those of organic origin, such as amber, jet, 
pearl, and coral, never crystallize, or possess regular external form. 
Such substances are termed amorphous. As a rule, gem minerals are 
those tending to occur in distinct crystals, since crystallization usually 
favors transparency and purity of substance. 




Hexagonal 
prism and 
pyramid 



40 



CUTTING AND MOUNTING 

The condition in which gems are found in nature is rarely such 
as, according to the general notion of human kind, exhibits their 
greatest beauty. In the state of nature, the surfaces of gems are gen- 
erally dull and lusterless ; their shape is irregular, and their mass is per- 
meated by flaws and imperfections. Moreover, the powers of reflection 
and refraction of light, which give gems their superior brilliancy and 
fire, can only be brought out in perfection when the stones are shaped 
with reference to their internal structure. Hence, from the earliest 
times, man has endeavored to increase the beauty of gems by bring- 
ing them to a condition of the highest possible polish and luster. 

The progress of this art has been a gradual and slow one; but in 
its present development it affords an opportunity for. the exercise 
of knowledge and skill of a high order. It is true that from time to 
time certain art critics, among whom was Ruskin, have urged that gems 
in their native state are more beautiful than when cut, but such views 
overlook the obvious enhancing of the optical qualities of a gem by a proper 
cutting. The mere facetting of a stone may be, as these critics claim, 
an expression of a somewhat vulgar taste ; but cutting a stone with 
reference to its optical structure applies an intelligent skill which can 
but prove enhancing to its natural beauty. Occasionally a diamond 
or ruby crystal is found of sufficient regularity of form and purity 
to make it available in its natural state for use as a gem ; but ordinarily 
the art of the lapidary is needed to bring from precious stones an exhi- 
bition of their full beauties, and fit them for the highest purposes of 
ornament. On the other hand, there is a common notion as to the 
amount of improvement that can be made in a stone by cutting or 
facetting, which is generally a mistaken one. There is no stone so dull 
and lusterless that some one will not think that it would be beautiful if 
it could only be cut and polished. But as a matter of fact, cutting or 
polishing usually changes the appearance of a stone very little, and a 
stone which is not attractive in color and transparency before cutting is 
not likely to be after. The skilled lapidary, it is true, can select the 
most favorable parts of a mass for cutting, but more than this he cannot 
do; and much disappointment may be avoided if only those stones are 

41 



cut which can be seen while in the rough to have the necessary desir- 
able qualities. 

The first effort on the part of man to improve upon the natural 
appearance of gems was confined to giving them a simple polish. 
At first only the natural surfaces were polished, but later the rough 
corners were rounded, and gradually the plan of giving them a symmet- 
rical shape developed. To this day, however, the treatment of gems 




A Ceylonese gem cutter of the present day 

in the Orient is confined largely to rounding and polishing the stones, 
with little alteration of their natural shape. The Kohinoor diamond 
in the form in which it reached England is an illustration of the 
unsymmetrical shape which is allowed by Orientals to be retained 
by even their most costly gems. The appliances by which this work 
of polishing and cutting gems is still performed in the East are of the 
crudest kind, and show little advancement from the earliest types used. 
The accompanying cut shows how a Ceylonese gem-cutter of the pres- 
ent day plies his trade. His wheel is supported on two upright pegs 
set in the floor timbers of his house. A wooden axle, on the end 

42 



of which is the disk for polishing, is inserted in these. The axle, 
and thus the disk, is rotated by pushing back and forth upon it with 
the right hand a long stick to which is fastened a string passing once 
around the axle. The stone to be polished is held against this revolv- 
ing disk by the left hand, either with the fingers directly, or by a stick 
to which the stone has been cemented. Abrasive powders and water 
are contained in bowls made by sawing cocoanut shells in two, and 
the abrasive is applied to the wheel by dipping the stone at intervals 
into the mixture. By this painfully slow and laborious process the 
polishing of the gem is in time accomplished. 

Among Occidental peoples, the cutting of gems was early carried 
to a much higher point than among Orientals. By both Greeks and 
Romans gems were given a symmetrical form, and they carried to 
a high degree of perfection the art of cutting cameos and intaglios 
from them. 

The different forms into which precious stones are cut at the pres- 
ent time may be arranged in two groups: (1), those having plane sur- 
faces; and (2), those having curved surfaces, although the two may 
be combined in the same cutting. The different forms under these 
subdivisions may be grouped, following Church, thus: 



1. Plane surface cuttings - - - - 



Brilliant. 

Step or Trap. 

Mixed or Brilliant Top. 



Table. 
Rose. 
( Single cabochon. 

Double cabochon. 
2. Curved surface cuttings - - - - -s TT 

Hollow cabochon. 

I Tallow top. 

Of these cuttings, those of the first group are usually used for 
transparent stones, such as the diamond, emerald, and ruby; and those 
of the second for translucent and opaque gems, such as the opal, 
turquois, moonstone, cat's -eye, and the like. The garnet is cut in 
both ways, the cabochon-cut garnet being called a carbuncle. 

The question as to which form of cutting should be used for any 
particular gem is one involving considerations of the mineral species 
and the peculiarities of each individual stone. On the one hand, it 
is desirable to avoid as little loss of the stone as possible; and on the 
other, to give it that shape and proportion which shall best bring out 
its luster, brilliancy, and color. Pale stones should, for instance, 
have greater depth than dark ones; the latter should be given more 

43 



" spread" and less depth. A well -cut stone is worth considerably 
more than a poorly cut one, even if the latter has a greater weight. 
Often in cutting a stone one-half and even more of its mass may 
be removed, and yet the stone be improved thereby. The brilliancy 
of a stone is increased, other things being equal, the larger the num- 
ber of facets which can be given it. The value of the stone must be 
taken into consideration in this connection, however. Stones of mod- 
erate value do not have their worth sufficiently increased by addition 
of numerous facets to warrant the expenditure of the extra time and 
labor that would be required to bring them to this condition. If a stone 
is strongly dichroic, as is iolite for example, the cutting must be in 






Side view of brilliant 



Brilliant seen from 
above. SK, skill facets ; 
QU, quoins or lozenges ; 
ST, star facets; CR, 
cross or skew facets; 
TEMP, templets or bezils 



Brilliant seen from be- 
low. SK, skill facets ; 
CR, cross facets 



such a direction as to bring out this quality in the highest degree. 
Similarly tourmaline, because of its dichroic properties, may make 
a dark and uninteresting stone if cut at right angles to the crystal- 
lographic axis, while if cut parallel to this axis it will make a bril- 
liant appearance and show two colors. Such stones as moonstone, 
labradorite, tiger's-eye, and others, which show chatoyancy only in 
certain directions, must obviously be cut with reference to this fea- 
ture. In transparent stones, the angle which the upper and lower 
facets make with each other should be a definite one, so as to reflect 
the light in the best possible manner. 

Considering briefly and in order the forms of cutting above men- 
tioned, we may note first the brilliant. The brilliant cut is said to have 
been invented by Cardinal Mazarin in his endeavors to introduce the art 
of diamond-cutting into France. It is now the form most commonly given 
diamonds and is employed for many other transparent stones as well. 
As will be seen from the above figure, it is made up essentially of 
two truncated pyramids joined by their bases, the upper pyramid 
leaving one -third and the lower pyramid two -thirds of the length 
of the stone. The upper pyramid is called the crown, the lower the 

44 







pavilion. The plane on which they join, and which represents the 
greatest breadth of the stone, is the girdle. The flat top of the upper 
pyramid is known as the table. It should be four-ninths of the breadth 
of the stone. . The corresponding termination of the lower pyramid is 
known as the culet, and this should have an area one-sixth to one-fifth 
of that of the table. The number of facets given these pyramids 
varies with different cuttings; but the typical has fifty-eight, which 
have individual names, as indicated in the diagram. 

The outline of the brilliant cut is not always so nearly circular 
as in the form shown in the diagram, although this is usual. Brilliants 

are sometimes cut so as to have a nearly square 
outline, or again they may be made triangular, 
or again oval. 

The proportions of the brilliant above given 
are not always followed by lapidaries, if it is 
deemed that they would involve the loss of too 
much material, or if the cutter believes it possible 
to improve the effect of the stone by depart- 
ing from them. The former consideration has 
weighed most largely in the cutting of some cele- 
brated diamonds, with the result that according 
to some critics the stones do not show to the best 

Trap or step cut as seen T rrn J.T IT- i T i - 

from above and below advantage. Ihus the Kohmoor diamond in its 

present form is said to be too broad for its depth, 
and the Regent too thick for its breadth. 

The second cutting to be noted is the trap or step cut. This is a 
favorite form of cutting for colored stones. It is a shallower cutting 
than the brilliant, and has a broader table. The outline is commonly 
oblong, in contrast to the more nearly circular form of the brilliant, al- 
though quadrilateral, hexagonal, and other outlines may be given. The 
rules of proportion are far less strict than those applied to the brilliant. 
The following form is a common one, however : Beginning with the table 
above, two sloping or step facets lead to the girdle, below which three to 
five or more sets, or zones of diminishing steps, extend to the culet. The 
latter has the general shape of the stone. The number of the facets is often 
increased over the above with advantage. A common fault with the 
step cut comes from making the table too broad, since the internal 
reflections from the lower facets are best seen, as Church states, through 
the sloping bezils of the crown, not through the flat surface of the table. 
The mixed or brilliant top cut is a combination of the brilliant and 
step cut. 

45 




Top and side views of 
table cut 



The table cut is a simpler cutting than either the step or brilliant. 
It consists simply of a table with beveled edges. It is an old form 
of cutting, and is generally superseded at the present day by forms 
with a greater number of facets. 

The rose cut has the crown facetted all over, 
the table of the brilliant being replaced by six 
triangular facets, and the other facets by eighteen 
triangular ones. The base is either made flat, or 
as a duplicate of the upper part, the latter cut 
giving what is known as the " double brilliant." 

The rose cut is especially useful for small or 
flat diamonds, as by means of it well-cut gems 
can be made from pieces of " rough " which are 
too small or too thin to make brilliants. 

Besides the brilliant and rose, which are stan- 
dard cuttings for the diamond, there are several quaint and fanciful 
cuts which are now more or less in vogue. One of these is the 
" pendeloque," a sort of double rose cut, and the " briolette," also a 
double rose cut of a general pear 
shape. The outline of the stone 
may be varied also, so as to be tri- 
angular, hexagonal, or circular. A 
form of diamond cutting which is 
now being extensively advertised is 
that called the " twentieth century " 
cutting. This is a double rose cut 
with eighty planes, forty above and forty below. It 
is made up essentially of two cones placed base to 
base, both completely facetted with planes, eight of 
which meet around each apex. The supposed supe- 
riority over the brilliant rests in the substitution of 
facets for the table and culet of the latter. 

The curved cuttings given to precious stones are 
all modifications of the form known as cabochon, the 
various shapes given being such as are best adapted 
to bring out the beauties of the individual stone 
which is to be cut. The different forms of the 
cabochon can be sufficiently well understood by refer- 
ence to the accompanying figures. The hollow cabo- 
chon serves the purpose of lightening the color of 
dark stones, and affording a place for inserting a foil. 

46 




Single cabochon 





Rose cut 



Double cabochon 




Hollow cabochon 



Flat or tallow-top 
cabochon 




Mixed cabochon 



The manner in which the actual work of cutting and polishing 
gems is performed by the most advanced methods of the present day 
varies somewhat with the kind of stone. Some stones naturally require 
a much harder abrasive than others, while different wheels and differ- 
ent polishing powders are suited to different gems. In general, the 
stone is reduced as nearly as possible to the desired shape by careful 
cleaving in the rough. If there is a natural cleavage much use can 
be made of this in bringing the stone to the desired shape ; if not, 
the work cannot be carried far in this manner. Large stones, if not 
too hard, can be sawed to a desirable shape with diamond or carbor- 
undum saws. After having been shaped as nearly as possible by one 
of these methods, the rough stone is then soldered to a metal handle, 
or cemented to a stick by means of wax or other adhesive substance, 
and ground to a rounded symmetrical shape on a flat, revolving wheel, 
the abrasive used being applied by means of water or oil. The wheels 
used are generally either of iron or copper, though lead, tin, and even 
wooden wheels are employed. For all gems except the diamond, the 
cutting of which can be carried on only by means of diamond dust, 
emery or ground corundum is the abrasive generally used,, although 
since the invention of carborundum this is employed quite extensively. 
After the stone has received a general rounding in this manner, the 
cutting of facets, one at a time, is begun. To maintain the exact 
I angle at which each facet is to be cut, a clamp is provided above the 
wheel, in which is fastened the handle on which the gem is soldered. 
By this means the stone is held against the wheel at the desired 
angle until the facet is cut. For facetting cheap stones the handle 
of the gem is sometimes held in the hand; but while the work 
can be done faster by this means it obviously cannot be performed 
so accurately. After the stone has received by grinding the proper 
number of facets, each of the size desired, the work of polishing must 
be performed. This is done in a similar way to the grinding, except 
that softer abrasives and softer wheels are used. Rouge, tripoli, and 
" putty powder " are the abrasives most commonly used for this pur- 
pose, they being applied dry or moist to wheels of leather, felt, or paper, 
against which the stone to be polished is held. 

Owing to its superlative hardness the cutting of the diamond must 
be performed by a somewhat different process than that of other stones. 
The facets upon a diamond are cut by rubbing together by hand two 
diamonds cemented upon sticks. After the facets have been outlined 
in this way they are ground and polished upon wheels to which diamond 
dust is applied, in a manner similar to that described for other gems. 

47 



The grinding and polishing of agates and other large stones are 
performed at Oberstein, Germany, on an extensive scale, in mills 
fitted up in the manner indicated in the accompanying cut. The 
wheels for grinding turn vertically instead of horizontally as is usually 
the arrangement when cutting small stones. They are made of sand- 
stone, are about five feet in diameter, and often a foot in thickness. 
Their edges are often fluted in different shapes, so as to give different 




Agate cutting at Oberstein, Germany. After Bauer 

desired forms. The piece to be cut is held by the workman by hand 
against the wheel until it has received the desired shape. After being 
ground it is polished on a wheel of hardwood with tripoli, this part of 
the work being usually performed by women and children. 

After a gem has been cut, the question of its proper mounting and 
setting must next be considered. While some gems are worn unmounted, 
as for instance the pearls of a necklace, the great majority are set in 
metal. This work is the especial art of the goldsmith or jeweler, and 
the laity usually take little pains to be informed in regard to it. 
There is room, however, for the development of a much higher taste 
in these matters than exists at present. The average buyer is con- 

48 



tent to know that the article which he purchases contains a sapphire, 
emerald, or diamond, representing so much intrinsic value, without 
considering whether the best use of it, from an artistic point of view, 
has been made; or whether for the same outlay much more pleasing 
effects might not have been obtained from other stones. In the group- 
ing of gems, with regard to effects of color, luster, texture, etc., certain 
combinations often seen are far from ideal, while others rarely seen 
would be admirable. Thus a combination of the diamond and turquois 
is not a proper one, since the opacity of the latter stone deadens the lus- 
ter of the former. The cat's-eye and diamond make a better combination, 
and so do the more familiar diamond and pearl. Colorless stones, such 
as the diamond or topaz, associate well with deep-colored ones, such as 
amethyst and tourmaline, each serving to give light and tone to the 
other. Diamond and opal as a rule detract from each other when in 
combination, since each depends upon " fire " for its attractiveness. 

Methods of mounting gems may be described as being essentially 
two in number, one the mount a jour, and the other the encased 
mount. The mount a jour, so called from two French words mean- 
ing to the light, is illustrated in the well -known manner of setting 
ring stones, by which the stone is held in place by a circlet of claws, 
exposing it to view on all sides. This mounting is especially suited 
to colorless and transparent stones without flaws, as it allows the 
freest play of light upon them, and permits their beauties to be fully 
seen. Jewels set in this way are, however, in greater danger of being 
lost, since the gem cannot be quite as firmly held as in the encased 
mount. In the encased mount the stone is set in a metal bed with 
only the top exposed. This mount is familiarly seen in many articles 
of jewelry. Being cemented to the metal bed the stone is in less 
danger of loss or injury than in the mount a jour. With the encased 
mount the effect of the stone can be much enhanced by the use of foils 
and paints, and many defects can be made invisible. Thus black specks 
in a stone can be overcome by setting against a black background, 
while a gold foil serves to bring out the fire of a garnet, for example, 
as an a jour setting could not. In all this work of setting gems and 
overcoming their defects, the Oriental peoples especially excel, and 
have done so for centuries. Examples of their work furnish, as a 
rule, the best models for study. 



VALUATION AND PRICE 

The unit of valuation by weight of gems in most countries is the 
carat. This term meant originally, according to some authorities, the 
weight of a bean of the coral tree (Ery 'thrina), known in Africa as kuara, 
and used there for weighing gold-dust. Others believe the term to be 
derived from the Greek word keration, said to be the name of the 
fruit of a variety of acacia having seeds of remarkably uniform size. 
As at present employed the weight of the carat expressed in grams 
is about one-fifth of a gram (200 milligrams), but varies in different 
countries from 197 to 216 milligrams. Th'e accepted weight in most 
of the large gem markets, such as Paris, London, and Berlin, varies 
little from 205 milligrams. This makes a carat weight a little over 3 
grains troy, the exact decimal being 3.165. Hence one grain troy =0.3 16 
carat, and one ounce troy=151.7 carats. The weight of the carat is 
usually given as four grains troy, but this is obviously not quite correct. 
The carat is subdivided into four equal parts, also known as grains, which 
evidently have not quite the weight of the troy grain, although the two 
are often confounded. The balances used for weighing gems are usually 
divided into sixty-fourths, and the fractional parts of a carat weight are 
then expressed by series of common fractions rather than by one fraction 
or a decimal. Thus a gem weighing 3|f carats might have its weight 
expressed in this manner, 3^, ^, ^. This is a record of the succes- 
sive divisions of the scale met in making the weight, not reduced to 
a simple fraction. 

The size of a stone of a given number of carats obviously varies with 
specific gravity of the gem; a two-carat sapphire, for instance, being a 
smaller stone than an emerald of the same weight. The size of diamonds 
of different carats weight is shown by the accompanying cuts, and they 
represent approximately the size of most gems of the same number of 
carats. 

The size of a stone, besides being indicated by weight, is frequently 
expressed by a number. This number refers to a scale of standard sizes 
adopted by jewelers, which runs from 1 to 50. Thus a stone of the size 
of No. 12 in the scale has a weight of one-eighth of a carat, No. 24 one- 
half a carat, No. 38 two carats, and so on. The scale thus affords a 

50 



means of distinguishing smaller differences of size than would be con- 
venient by weight alone. 

The measurement of the weight of pearls differs from that of other 
gems in that pearls are measured by their weight in grains. The grain 
here employed is not the troy grain, however, but four-fifths of it, so 
that four troy grains are equal to five pearl grains, and a troy ounce 
contains 600 pearl grains. 

So far as the more precious gems are concerned, it may be noted that 
their price increases in a much higher proportion than does the weight. 
According to a rule, sometimes called Tavernier's and sometimes Jeffries' 
rule, the price should increase as the square of the weight. Thus if a 




Exact sizes of diamond brilliants from 34 to 100 carats weight 



carat stone is worth $80, a five-carat stone would be worth not five 
times $80=$400, but 5 2 or 25 times $80=$2,000. The rule, how- 
ever, affords no more than an approximation of the value, it giving in 
general too high a result. Some gems, such as amethyst, topaz, and 
others, increase in value only in about the same proportion as they increase 
in weight, since large stones of these species can be readily obtained. 

In addition to weight, quality is a factor largely affecting the price of 
precious stones. To be of the first quality, or first water, a gem must be 
of uniform luster and color, must be free from cracks of every kind, from 
bubbles, and if transparent, from inclusions of every sort, cloudy spots 
or streaks. Any of these flaws can usually be distinguished by holding 
the stone between the eye and the light, or they are more clearly brought 
out if the stone is immersed in a liquid with high refractive power, such 
as oil of cloves, linseed oil, or even kerosene. These flaws may occur in 
the rough stone, or the operation of cutting may produce little cracks, 
called feathers, which injure the value. Obviously, therefore, to be sure 
of obtaining a flawless gem, it should be purchased after the operation 
of cutting has been completed. 

The value of rough stones compared with those cut varies with the 

51 



variety and size of the stones. Not only does cutting reduce the stone in 
size, but the cost of cutting must be taken into consideration. The latter 
may represent almost the entire value of stones the raw material of 
which is abundant and cheap, as is true of many of the varieties of 
quartz. In the case of diamonds the cost of cutting adds about 50$> to 
their value. 

The price of gems, besides varying with quality and species, is de- 
pendent like that of other commodities upon supply and demand, which 
are in turn affected by discoveries of new sources, and by changes of 
fashion. Thus the discoveries of diamonds in Brazil and South Africa 
respectively caused a fall in the prices of this gem at each of these 
periods because of the increased supply afforded. In 1750, just before 
the influx of Brazilian diamonds into Europe, one-carat stones were 
valued at $40. Shortly after, when the supply from Brazil poured into 
the market, they fell to a value of only $5. In 1791 this price had 
risen to $30. This fell again to $20 during the French wars of 1848, but 
by 1865 had risen to nearly $100, which is not far from the present price. 
At the present time the emerald has reached an unprecedented price, 
because while the demand is steady the supply has almost entirely failed. 
On the other hand, the sapphire has fallen about 25$ in value in the last 
twenty years on account of the discovery of new fields. In some cases, 
however, the failure of supply of a little-used gem may cause the 
demand for it to cease, as has happened with the Italian diopside. 

The price of the four gems, diamond, ruby, sapphire, and emerald, is 
on the whole little influenced by changes of fashion, for they seem to 
be always in demand. Most of the other gems, however, vary in price 
with the fashion, being at one time much in vogue and again almost for- 
gotten. Thus topaz is now little prized, but Kunz states that the mines 
of this gem in Spain have been bought and are being held by a French 
company in anticipation of a return of the stone to fashion. This might 
cause a demand for it equal to that of forty years ago, when it brought 
from $4 to $8 per carat. 

As gems are objects of luxury, and not of necessity, the demand for 
them is greater, and hence their price is higher, in times of prosperity. 
Vice versa in hard times, or periods of financial depression, prices of 
gems fall. The period following the French Revolution witnessed a great 
lowering of the prices of gems, partly because the previous extrava- 
gances of the French court in this direction had been one of the sources 
of popular discontent, and partly because of the general financial depres- 
sion. At the present time in the United States the magnitude of the 
gem trade is greater than ever before. 



The skill with which a stone is cut should be taken into considera- 
tion in valuing it, although this is a matter upon which only an expert 
is competent to give an opinion. Of two stones of the same weight 
and equal quality, one may be worth ten times as much as the other 
because more skilfully cut. Further, the exact qualities desirable in 
any particular gem are points to be learned by long skill and experience, 
and stones possessing these qualities command much higher prices 
than the ordinary. 



53 



IMITATION GEMS AND HOW TO 
DETECT THEM 

The art of imitating gems has reached a high degree of perfection, 
and while the substitutes thus prepared have legitimate uses, the tempta- 
tion to palm them off on the unsuspecting for real gems, at or near 
the price of the genuine, is often too strong to be resisted. It becomes 
important, therefore, that every one purchasing precious stones should 
be acquainted with the characteristics of the false as well as of the 
real, and unless purchasing of a perfectly reliable dealer should sub- 
ject the offered stone to the most careful scrutiny. Tourists are espe- 
cially liable to deception of this sort, since their purchases must be 
largely made of itinerant venders, with whom they are not acquainted. 
The Persian turquois venders, knowing the liability of some of their 
wares to fade, are accustomed to leave for parts unknown as soon 
as their stock is disposed of, and gem-sellers of other nations often 
exhibit similar propensities. 

Emanuel tells of a man who left his business in his own country, 
and at considerable expense went to England to sell a quantity of stones 
which he had been assured were diamonds, only to find on arrival there 
that they were simply quartz. This experience in one form or another 
has doubtless been repeated countless times, and should serve to show 
the importance of knowledge on the part of all purchasers of gems of the 
features which make them intrinsically valuable. 

It may be said in general that the one quality of most gems which 
cannot be successfully duplicated is their hardness. The best simple 
protection therefore against purchase of a glass imitation for most precious 
stones will be found in a test of this property. Glass is softer than 
most precious stones, and hence is much more easily scratched than 
they. It will yield to the file, while they will not. This test should 
of course be made so as to avoid injury of the stone, for often the 
girdle of a gem cut as a brilliant is as delicate as a knife edge, and 
great care should be used in testing it. If a file be not convenient, 
a fragment of quartz can usually be obtained, and affords an accurate 
means of testing hardness, since the hardness of quartz is 7, and that 

54 



of glass rarely over 5. An aluminum pencil also affords a safe means 
of testing hardness. Drawn over glass it leaves a white, silvery line, 
but on hard gems little if any mark. In respect to color, luster, and 
even specific gravity, glass may be made to imitate almost any gem. 
Even natural looking flaws can be made in a glass imitation by dexter- 
ous hammer blows. Nevertheless glass can often, though not always, 
be distinguished from a mineral by the fact that in a piece of glass 
minute air bubbles may be seen on examining it with a lens. These 
bubbles generally differ in shape and number from any found in natural 
minerals. Glass also has a characteristic conchoidal fracture not quite 
like that usual to minerals. Jj'ue gems are colder to the touch than 
glass as a rule, although glass is colder than such substances as jet, 
amber, and pearl, for which it is often substituted. The^colder feeling 
of true gems comes from their being better conductors of heat than glass, 
so that they take away warmth from the hand more rapidly. For the 
same reason most true gems when breathed upon acquire a thicker coat-, 
ing of moisture than glass and lose it more quickly than does that sub- 
stance. In the application of these simple tests jewelers often become 
very skilful, and if the stones are not too small can pick out a diamond, 
sapphire, or other gem from a whole bagful of glass imitations by the 
above distinctions alone. When in the rough, a useful distinction of 
glass from most gems is to be found in the easy fusibility of the former 
before the blowpipe. While most gems are practically infusible in this 
way, glass is easily fused, and hence the trial of a splinter of the sub- 
stance before the blowpipe affords a test of value. The distinction of 
glass from minerals by an observation of their behavior in polarized light 
can be made without injury to the substance tested, and with reliable 
results. To be sure, the distinction of glass from diamond, spinel-ruby, 
or other singly refracting gem, cannot be made in this way ; but when 
the stone is doubly refracting, as is the case with the majority of species, 
such investigation affords one of the surest and most convenient means 
of identification. The use of the dichroscope or polarizing microscope 
for this purpose has already been explained. 

The glass used for making imitation gems is usually one having a 
high percentage of lead in its composition. The lead makes it soft but 
gives it great brilliancy. The glass is usually known as paste, or strass, 
the latter name being from the inventor, Strass of Strassburg, who 
invented the mixture during the seventeenth century. Uncolored it 
affords a good imitation of the diamond, and when colored with various 
metallic oxides, remarkably accurate likenesses of different gems can be 
obtained. 

55 



Besides counterfeits wholly of glass, many precious stones are adul- 
terated, so to speak, by making a portion of a genuine stone, and 
employing glass for the remainder. Such fabrications are called 
doublets, the upper part of the stone being of course the genuine 
portion. The application of a file to the upper and lower parts in 
turn will usually detect the fraud; or if the two parts are cemented 
together by gum mastic, as is usually done, they will separate on 
being soaked in warm water. The union can also often be seen on 
holding the cemented stone up to the light. Occasionally, however, 
the two are fused together, in which case soaking would not separate 
them, nor would the plane of union be visible. A desired color is some- 
times given to doublets by inserting a foil between the two portions. 

Besides the use of glass in place of precious stones, an effort is 
often made to substitute a cheaper stone for the one represented. 
Quartz, white sapphire, and topaz may thus be substituted for diamond, 
pink topaz for ruby, and so on. In such cases the distinction of hard- 
ness is not as marked as if glass is employed; but the test with light 
can usually be made, and determination of the specific gravity, or other 
property, often serves to detect the counterfeit. 

Besides employing the above-named devices, deception is sometimes 
achieved by making a large stone of two smaller ones of the same 
mineral cemented together. Again, inferior stones may have their backs 
painted to give them a desired color. The practice of setting a stone 
against a foil in order better to bring out its color or luster as, for 
instance, mounting an opal or moonstone on black, or garnet against 
silver is not considered illegitimate, and should by all means be 
employed when the effect of a stone can thus be enhanced. 

The difficulties of detecting fraudulent gems will obviously be greatly 
increased if the stones are set. Gems should, therefore, always be pur- 
chased loose if possible, especially costly ones. 

On the whole, the accurate distinction of gems, or detection of frauds, 
requires knowledge of the different physical characters of each species, 
such as hardness, specific gravity, and behavior in polarized light. 
A single test is rarely sufficient to identify a gem; but by the use 
of several, perfectly trustworthy results can be obtained. 



56 



SUPERSTITIONS REGARDING GEMS 

From the earliest times and among all peoples there seem to have 
been sentiments and superstitions connected with gems. Not only 
was the power of driving away evil spirits and producing all sorts 
of " luck " long attributed to them v but as late as the beginning 
of the eighteenth century reputable physicians were accustomed to mix 
fragments of them in their medicines and to use them as charms. /To 
this day amber is kept in stock by druggists in Paris for use in filling 
prescriptions. xThe Chinese still use powdered pearls, coral, and other 
gems in medicine, and various Indian tribes of North America ascribe 
great medicinal value to one gem or another. In the writings of Greek 
and Roman writers are found many statements indicating belief in 
the medicinal and other virtues of gems. It was in the Middle Ages, 
however, that these opinions seem to have been most widely and firmly 
held, so far as it is possible to learn of them through history. 

The following passage from Marbodus, a writer of the latter part 
of the eleventh century, is a good example of some of the virtues 
attributed to gems in that time:* 

"The chalcedony, if blest and tied round the neck, cures lunatics. 
Moreover, he that wears it will never be drowned or tempest-tossed. 
It also makes the wearer beautiful, faithful, strong, and successful in 
all things. One ought to engrave upon it Mars armed, and a virgin 
robed, wrapped ha a vestment, and holding a laurel branch; with a per- 
petual blessing. 

'Aristotle, in his book on gems, says that an ^emerald hung from 
the neck, or worn on the finger, protects against danger of the falling 
sickness. We therefore commend noblemen, that it be hanged about 
the necks of their children that they fall not into this complaint. 
The emerald is approved in all kinds of divination; in every busi- 
ness if worn it increases its owner's importance, both in presence and 
in speech. 

"A sard, of the weight of twenty grains of barley, if hung round 
the neck or worn on the finger, the wearer shall not have terrible 

* King, Antique Gems, p. 432. 

57 



or disagreeable dreams, and shall have no fear of incantations or 
of witchcraft. 

"The beryl is a large and transparent stone. Engrave upon it 
a lobster, and under its legs a raven, and put under the gem a vervain 
leaf, inclosed in a little plate of gold; it being consecrated and worn, 
makes the wearer conqueror of all bad things, and gives protection 
against all diseases of the eyes. And if you put this stone in water, 
and give this water to one to drink, it cures stoppage of the breath 
and hiccups, and dispels pains of the liver. It is useful to be worn, and 
he that hath this gem upon him shall be victorious in battle over all his 
foes. It is found in India, like unto the emerald, but of a paler cast. 

"The sard is good to be worn, and makes the person beloved by 
women; engrave upon it a vine and ivy twining round it. 

"The casteis (callais turquois) is good for liberty, for he that hath 
consecrated it, and duly performed all things necessary to be done in 
it, shall obtain liberty. It is fitting to perfect the stone when you have 
got it, in this manner : Engrave upon it a beetle, then a man standing 
under it; afterwards let it be bored through its length and set on 
a gold fibula (swivel); then being blest and set in an adorned and 
prepared place, it will show forth the glory which God hath given it." 

Some of the other traditional virtues of gems ascribed chiefly in 
the Middle Ages, but many doubtless of earlier origin, are as follows : 

Agate was believed to have the power of averting storms, counter- 
acting poison, and stemming the flow of blood. A black agate with 
white veins was considered a potent talisman against every danger, 
and to have the power of rendering the wearer invisible. 

Amber worn in beads about the neck or wrist was regarded a cure 
for sore throat and ague, and a preventive of insanity, asthma, dropsy, 
toothache, and deafness. 

The bloodstone prevented death from bleeding. 

The cat's-eye warned its wearer of danger, storms, and troubles, 
and was a charm against witchcraft. It was also a cure for croup when 
applied locally. 

Precious coral prevented blight, caterpillars, storms, and locusts, 
and was a charm against lightning, whirlwind, shipwreck, and fire. 
Taken internally it was a cure for indigestion. 

The diamond was a talisman against danger, and gave hardiness, 
fortitude, and manhood to its owner. 

The emerald gave immortality, won the favor of rulers and paci- 
fication of enemies. If its wearer was unmarried it rendered him 
invisible. 

58 



The garnet was a preventive of fever and dropsy, and rendered 
its wearer agreeable, powerful, and victorious. 

The hyacinth gave second sight, promoted sleep, and preserved 
from thunderstorms and pestilences. 

lolite foretold storms by changing hue. 

Jasper had the power of stopping overflowing blood, or water, and 
was a preventive of poison. 

Jet induced fertility. 

Moonstone was believed to contain an image of the moon, which 
grew clear upon days and occasions fortunate to its owner, and dim 
with the reverse. It was thought to wax and wane with the moon 
and was a cure for epilepsy. 

The onyx exposed its wearer to lawsuits, bad dreams, and demons. 
If a sard were worn with it, however, these evil influences were counter- 
acted. It symbolized and insured conjugal felicity. 

The opal faded upon the insincere, deceitful, and impure ; but when 
worn by the innocent united the special virtues of all gems. 

The pearl insured entrance to Heaven; but this privilege might 
be lost by carelessness of life. 

Quartz if burned averted storms, and powdered and mixed with 
water cured serpents' bites. 

The ruby preserved its owner's house or vineyard from lightning, 
tempest, and worms if the former were touched by it. It was also 
a disinfectant and preventive of infectious diseases. Bruised in water 
it relieved weakness of the eyes, and cured liver complaints. 

The sapphire was a preventive of despair and fire; a curative 
of madness and boils. 

The topaz was good for burns, and if thrown into boiling water 
deprived it of its heat. It prevented melancholy and cured hemor- 
rhages. Its internal brilliancy was believed to follow the phases 
of the moon. 

Tourmaline when heated was capable of charming away pain, such 
as toothache, headache, etc. 

A turquois grew pale if its owner became sick, and lost its color 
at death until placed upon a princess's finger. It prevented injury 
in case of a fall. Held suspended in a glass it told the hour by 
strokes against the sides. It was a cheerer of the soul and insured 
prosperity. 

Such opinions regarding the virtues of gems were not confined to the 
lower classes but were held generally. There is little doubt that rulers 
were accustomed to carry their gems to the battle-field with them for the 

59 



sake of the protection they might afford and victory they might give, 
for Charles the Bold lost his gems, among which is said to have 
been the Florentine diamond, at the battle-field of Nancy in this way, 
and there are other instances indicating that the practice of carrying 
gems for this purpose was common. 



60 



BIRTH-STONES 

Another interesting illustration of the regard in which precious 
stones have been held is the custom, which survives to some extent to 
the present day, of making a particular gem appropriate to a certain 
month of the year. 

Perhaps the first arrangement of gems into a group of twelve of 
which we have any record is that in the Book of Exodus. Here in the 
twenty-eighth chapter, verses 17-19, are prescribed in order twelve 
precious stones, which shall be set in the breastplate of the high 
priest. The list is repeated in the thirty-ninth chapter of the same 
book, verses 10-12. In the context it is prescribed that the stones 
shall be set in four rows, and that upon them shall be engraved the 
names of the children of Israel, one for each stone. As to the par- 
ticular gems which are indicated by the Hebrew words, authorities 
differ; but in the Authorized Version of the Bible they are given as 
follows : 

Sardius, topaz, carbuncle, 

Emerald, sapphire, diamond, 

Ligure, agate, amethyst, 

Beryl, onyx, jasper. 

It is not probable, however, that these names indicate in each case 
the corresponding stones of modern usage. Thus, it is quite unlikely 
that the Hebrews could have engraved a name upon the diamond 
even if they could have obtained one of sufficient size. Again, the 
words emerald and carbuncle are undoubtedly interchanged in the 
above list, and the ancient topaz is known to have been the modern 
chrysolite. In the Revised Version the word jacinth is substituted for 
ligure, and amber is given as a marginal rendering for the same. There 
are also given marginal renderings for others of the gems as follows: 
Ruby for sardius, emerald for carbuncle, carbuncle for emerald, sardonyx 
for diamond, chalcedony for beryl, and beryl for onyx. The modern 
equivalents of the terms recognized by secret orders which use them 
in symbolism are: 



61 



Carnelian, chrysolite, emerald, 
Ruby, lapis-lazuli, onyx, 
Sapphire, agate, amethyst, 
Topaz, beryl, jasper. 

Two lists of precious stones, quite similar to those of the Book of Exo- 
dus, are given in other places in the Bible, one in Ezekiel xxviii. 13, 
where " every precious stone " is said to have been the covering of the 
king of Tyre, and again in Revelation xxi. 19-20, where twelve differ- 
ent precious stones are mentioned as garnishing the foundations of the 
wall of the Holy City. The names and order of these in Ezekiel are, 
in the Authorized Version, as follows : 

Sardius, topaz, diamond, 
Beryl, onyx, jasper, 
Sapphire, emerald, carbuncle. 

To these the Septaguint adds the following: 
Chrysolite, ligure, agate. 

The Revised Version gives marginally, ruby for sardius, carbuncle 
for emerald, and emerald for carbuncle. In Revelation the list as 
given in the Authorized Version reads as follows: 

Jasper, sapphire, chalcedony, 
Emerald, sardonyx, sardius, 
Chrysolite, beryl, topaz, 
Chrysoprase, jacinth, amethyst. 

The marginal renderings give lapis-lazuli for sapphire, and sapphire 
for jacinth. 

Though in each of these lists only twelve precious stones are men- 
tioned, there is nothing to indicate that their use was in any way 
connected with the months of the year. Just when it became the 
custom to designate each month by a particular gem, or how the 
custom originated, it is impossible to determine. The custom seems to 
have sprung up in modern Europe some time during the fifteenth or 
sixteenth century. Whether it originated in the twelve gems of Aaron's 
breastplate, as many believe, or was introduced by astrologers from the 
Arabians, as others think, is not yet known. 

The modern practice of considering the stone of each month espe- 
cially appropriate to persons born in that month is probably still more 
recent in its origin. In former times gems could be possessed only 
by rulers or the very wealthy, so that their general use in the above 
manner was not possible. But now that nearly every one can own 

62 



a gem of some kind, the possession of "birth-stones," and the attach- 
ment of special sentiments to them, has become common. The custom 
is a pretty one, and is to be commended, for the stones are imperish- 
able, and the sentiments ascribed to them represent the accumulated 
traditions of many ages, races, and peoples. 

As to the particular stone which is to be considered appropriate 
to each month usages differ. Such differences have doubtless arisen 
from the desire to introduce gems which were formerly little known 
or unattainable on account of their cost, as substitutes for stones for- 
merly prized but now held of little value. Thus the precious opal, 
now within the reach of all, was rare in former times. By some it 
is now used as the birth-stone of the month of October, while others 
retain the beryl. The diamond has been introduced in modern practice 
in quite a similar way. The carnelian and chrysolite, by some still 
used for the months of August and September, are stones held of little 
worth at present, and hence others are usually substituted. The par- 
ticular order and kind of stones adopted in the colored plate which serves 
as a frontispiece to this work is given in accordance with some verses 
quoted in a pamphlet first published by Tiffany & Company, of New 
York, in 1870. The author of the verses is not known, nor is it known 
by just what authority these gems were chosen. The choice, however, 
seems as satisfactory as could be made. 

JANUARY 

By her who in this month is born, 
No gems save garnets should be worn; 
They will insure her constancy, 
True friendship, and fidelity. 

FEBRUARY 

The February-born shall find 
Sincerity and peace of mind, 
Freedom from passion and from care, 
If they an amethyst^ will wear. 

MARCH 

Who in this world of ours their eyes 
In March first open shall be wise, 
In days of peril firm and brave, 
And wear a bioodstone to their grave. 

APRIL 

She who from April dates her years, 
Diamonds shall wear, lest bitter tears 
For vain repentance flow; this stone, 
Emblem of innocence, is known. 
63 



MAY 



v WhQ first beholds the light of day 

In spring's sweet flowery month of May, 
And wears an emerald all her life, 
Shall be a loveoancThappy wife. 



JUNE 



Who comes with summer to this earth, 
And owes to June her hour of birth, 
With ring of agate on her hand 
Can health, weaMi, and long life command. 



JULY 



The glowing ruby shall adorn 
Those who in July are born; 
Then they'll be exempt and free 
From love's doubts and anxiety. 



AUGUST 



Wear a sardonyx, or for thee 

No conjugat~felicity; 

The August-born without this stone, 

'Tis said, must live unloved and lone. 



SEPTEMBER 



A maiden born when September leaves 
Are rustling in September's breeze, 
A sapphire on her brow should bind 
'Twill cure diseases of the mind. 

OCTOBER 

October's child is born for woe, 
And life's vicissitudes must know; 
But lay an opal on her breast, 
And hope will lull those woes to rest. 

NOVEMBER 

Who first comes to this world below 
With drear November's fog and snow, 
Should prize the topaz's amber hue 
Emblem of friends and lovers true. 

DECEMBER 

If cold December gave you birth, 
The month of snow and ice and mirth, 
Place on your hand a tmquois- blue ; 
Success will bless whate'er you do. 
64 



Other groupings of precious stones in lists of twelve are those 
which assign one to each of the twelve tribes of Israel and to the 
twelve apostles. The list of the former is thus given by Alcott: 



Naphtali 
Asher - 
Dan - 
Gad 
Simeon 
Reuben 



Jasper. 

Onyx. 

Beryl. 

Diamond. 

Sapphire. 

Emerald. 



Benjamin - 
Maiiasseh 
Ephraim - 
Zebulon 
Issachar 
Judah - 



Amethyst. 

Agate. 

Ligure. 

Garnet. 

Topaz. 

Euby. 



Tassin however gives a somewhat different list obtained from an old 
silver breastplate employed as an ornament for a manuscript copy of the 
Torah, or Pentateuch, used in an ancient synagogue and now in the U. 
S. National Museum. This is as follows: 



Naphtali 


- Agate 


Benjamin - 


- Jasper 


Asher 


Beryl 


Joseph - 


Onyx 


Dan ... 


- Topaz 


Levi - 


- Garnet 


Gad 


Amethyst 


Zebulon - 


Diamond 


Simeon . 


- Chrysolite 


Issachar 


- Sapphire 


, Reuben - 


Sard 


Judah 


Emerald 


The list of 


the gems of the 


twelve apostles 


is thus given by 


Emanuel : 








Peter - 


- Jasper. 


Matthew 


- Chrysolite. 


Andrew 


Sapphire. 


Thomas 


Beryl. 


James - 


- Chalcedony. 


Thaddeus 


- Chrysoprase. 


John 


Emerald. 


James the Less - 


Topaz. 


Philip - 


- Sardonyx. 


Simeon - 


- Hyacinth. 


Bartholomew 

k 


Cornelian. 


Matthias - 


Amethyst. 



65 



DIAMOND 

The diamond is generally conceded to be the most beautiful as it 
is the most important of precious stones. A few other stones exceed 
it in value, weight for weight; but in total importance as an 
article of commerce other gems are hardly to be compared with 
it. Out of thirteen and one-half millions of dollars' worth of precious 
stones imported into the United States in 1900, twelve million dollars' 
worth were diamonds. Not all this amount was employed for jewelry, 
since there is a large utilization of the stone for industrial purposes; 
but even for jewelry the diamond has a largely preponderating use. 
Its points of superiority are its hardness, its high refractive powers, 
and its adamantine luster. In all these qualities it excels any other 
known mineral. When in addition to these it exhibits different body 
colors, as is sometimes the case, the most highly prized of gems are 
produced. 

In composition the diamond is pure carbon, thus not differing chem- 
ically from graphite, or such forms of carbon as lamp-black, bone-black, 
etc. It is crystallized, but this can be said of graphite as well. Why 
carbon should assume the form of diamond in one case and graphite 
in another, as well as being amorphous in other occurrences, is not 
known. Such behavior of a substance is known as dimorphism, and 
numerous illustrations of it are to be found in nature. 

Being pure carbon, diamond can be burned in the air. The finely 
divided dust can be burned in the ordinary blow-pipe flame, and for 
stones of ordinary size a temperature of about 900 C. is sufficient. 
The possibility of consuming the diamond by heat is said first to have 
been suggested by Sir Isaac Newton, who reasoned from the high 
refractive index of the stone that it was " an unctuous substance 
coagulated," and hence probably combustible. Following this sugges- 
tion two Italians, Averani and Targioni, succeeded, in 1695, in burning 
some diamonds in a furnace, and since then the experiment has been 
repeated many times. The diamond does not fuse in burning, but 
after becoming heated to redness gradually grows smaller, emitting 
sparks, till it entirely disappears. It leaves no ash, except in the 
case of the impure form known as carbonado. The gas given off has 

66 



been collected and analyzed, and found to be carbon dioxide, just as 
would result from the combustion of other forms of carbon. If pro- 
tected from the air or free oxygen, the diamond can be exposed to 
high heat without change. 

Being a crystallized substance and excessively hard, the diamond 
is usually found in the form of more or less perfect crystals. These 
have forms such as the cube, octahedron, etc., which belong to the 
isometric system, and it is in this system that the diamond crystal- 
lizes. The crystals do not possess, however, the highest isometric sym- 
metry, but belong to the class designated by Groth as hexakistetrahedral, 
being tetrahedral with in- clined face hemihedrism. 

Of the forms occurring, the / X '\x v octahedron, which is the 

first shown in the accom- / V\ panying cut, is best suited 
for cutting. It is very /_^^ V^ common for the faces to 
be curved instead of flat, \ // an( ^ ^ snow etching 

figures of various kinds. \. // The crystals are often con- 
siderably distorted so as ^^ to produce pointed and 







Common forms of diamond crystals 

rounded forms, and twin crystals are common. Although so excessively 
hard, the edges of the crystals, as found in the beds of streams, are 
often rounded from the wear of the other pebbles, probably chiefly 
quartz. Only the wear of centuries could produce such a result, how- 
ever; for, as is well known, it is only with its own dust that the 
diamond can be abraded to any appreciable degree by any of the 
means now used for cutting it. 

One important property of crystallized diamond is that of cleavage 
parallel to the faces of the octahedron. This cleavage is of much 
service in preparing the gem for cutting, as by taking advantage 
of it, broad, flat surfaces can be obtained without grinding. This 
property also distinguishes diamond from quartz, for which its crys- 
tals, as found in sands, are sometimes mistaken. Quartz has no cleav- 
age. The fracture of the two minerals is the same however, being 
conchoidal. 

The massive forms of the diamond known as bort and carbonado 

67 



possess little or no cleavage, thus increasing their value as abrasives 
and for setting in drills, saws, etc. The true bort occurs as rounded 
forms made up of a confused aggregate of crystals, and is harder than 
ordinary diamond. Fragments of crystals of no value as gems, or any 
crude diamond dust, are also known as bort in trade. Carbonado 
is a name given to black diamond, which has more or less crystal- 
line structure. This graduates into the crystallized mineral. Either 
of these is more valuable than the crystallized diamond for industrial 
purposes, although of no value as gems. 

Usually the diamond is colorless or white, although shades of yellow 
are also common. It is also known in shades of red, green, and blue, 
and in brown and black. The two latter are rarely transparent, and 
grade into bort and carbonado. 

About half the diamonds found are tinged to some degree. If the 
color is but slight, the stone is considered less valuable than if per- 
fectly colorless; but a diamond of pronounced color is the most valu- 
able gem known. 

Among colors of diamonds, blue is the rarest. The largest and 
most valuable colored diamond known is the Hope Blue, weighing 
44 carats. This is valued at about one hundred thousand dollars. 
It has a brilliant deep blue color and is without a flaw. A deep blue 
diamond, weighing 67^ carats, was long worn in the French crown, 
but it was stolen in 1792 and has never been recovered. Red diamonds 
vary in hue from ruby-red to rose, the latter being the most common. 
No large red diamonds are known, the largest being one of 32 carats 
in Vienna. Another famous one is that in the Russian treasury, 
for which Paul I. paid one hundred thousand roubles. It is of a ruby 
color. The finest green diamond known is the "Dresden Green" pre- 
served in the Green Vaults of Saxony. It was purchased by August the 
Strong in 1743 for sixty thousand dollars. It is apple-green in color 
and weighs 40 carats. Diamonds of yellow color are comparatively 
common, many of the Cape diamonds being lowered in value by possess- 
ing a yellow tinge. It is said that this injurious yellow tinge can be 
overcome by dipping the stone several times in a solution of potas- 
sium permanganate, the violet color of the latter neutralizing the yellow 
of the diamond. The yellow tinge usually also disappears in artificial 
light. Of large diamonds possessing a yellow color the Florentine and 
the Tiffany are the best known. The color of colored diamonds is gen- 
erally permanent, but that of some is said to fade on exposure to light. 
It can also be destroyed or changed by heat. 

The luster of the diamond is a peculiar one, and such as is possessed 



by few other minerals. In reference to its occurrence in the diamond 
it is known as the adamantine luster. It combines the peculiarity 
of an oily luster with that of glass and that of a metal. It is doubt- 
less due to the high refractive power of the mineral, which causes 
more than the ordinary number of rays of light to come to the eye. 
In the impure forms of diamond the greasy or oily luster becomes 
more pronounced. Once the eye becomes accustomed to the peculiar 
luster of diamond the stone may easily be distinguished by it from 
glass or minerals with a vitreous luster, such as quartz. Certain other 
minerals, however, such as cerussite, zircon, and to some extent sphene, 
exhibit the adamantine luster. In the glass known as strass, used 
to make imitation diamonds, the adamantine luster is well reproduced. 

Diamond is usually transparent, but it may be translucent, and even 
opaque, especially the black varieties. Even otherwise transparent 
diamond often contains inclusions which cloud and interrupt its clear- 
ness. These constitute the "flaws" which so often injure the value 
of a diamond and prevent it from being of the " first water." These 
inclusions may be simply small cavities, sometimes so numerous as 
to make the stone nearly black; or they may be particles of other 
minerals, such as chlorite, hematite, or carbonaceous matter. If the 
latter, the flaws can sometimes be burned out by careful heating. 

As already remarked, the refractive power of the diamond is very 
high. The rays of light entering it are bent at a high angle, causing 
a large degree of what is called total reflection within the stone. 
The effect of this is to light the stone's interior. Moreover, the rays 
of light are concentrated on a smaller part of the surface than is the 
case with less highly refracting minerals, and thus also internal illumi- 
nation is produced. The most important result of the high refractive 
power of the diamond is the wide dispersion of the spectrum, causing 
the red rays to be widely separated from the blue rays, and strong 
lights of one color to be transmitted to the eye, as could not be the 
case were the different rays less widely separated. It is this power 
of flashing different colored lights which gives the diamond one of its 
chief charms. The index of refraction ranges from 2.40 for the red 
rays to 2.46 for the violet rays. Ordinary glass has an index of refrac- 
tion for the red rays of only 1.52, and for the violet 1.54, making the 
spectrum only about half as long as that produced by the diamond. 

Another pleasing property of the diamond is the fact that it is 
usually more brilliant by artificial light than by natural, although some 
individual stones have a reverse behavior. 

Diamond is much the hardest substance known in nature, and as 



the proverb says, only the diamond is able to " cut diamond." It is 
ranked 10 in the scale of hardness, corundum being the next below 
it. It is really separated by a wide gap from the latter mineral, 
however, and its hardness is as much greater than that of corundum 
as that of corundum is greater than that of the first mineral in 
the scale. This hardness of diamond affords a ready means of 
identifying it, as it will scratch all other substances. It is popularly 
supposed that diamond is the only mineral which will scratch 
glass to any extent, and a stone found is often reported to be 
diamond because it will do this. As a matter of fact, however, 
all quartz will scratch glass, and the harder minerals, garnet, 
topaz, beryl, and others will do so easily. Minerals which will scratch 
glass are, therefore, common. The diamond cuts glass instead of scratch- 
ing it, and is the only mineral that will do this. Although the diamond 
is so hard, it is not tough, and can be easily broken with the blow 
of a hammer. It was a tradition of the ancients that if a diamond 
were put upon an anvil and struck with a hammer, both hammer and 
anvil would be shattered without injuring the diamond in the least. 
One occasionally hears this statement made even at the present day. 
It is entirely untrue, however, the diamond being as brittle as at least 
the average of crystallized minerals. 

The specific gravity of the diamond is about three and one-half times 
that of water, determinations showing variations between 3.49 and 3.53. 
Carbonado is lower, ranging between 3.14 and 3.41. Diamond is thus 
a comparatively heavy mineral, the only ones among the gems which 
much exceed it in specific weight being hyacinth, garnet, ruby, 
sapphire, and chrysoberyl. 

Diamond becomes strongly electric on friction, so that it will pick 
up pieces of paper and other light substances. It does not retain its 
electricity long, however, usually not over half an hour. It is not 
a conductor of electricity, differing in this respect from graphite, 
which is a good conductor. Diamond becomes phosphorescent on rub- 
bing with a cloth, giving out a light which is visible in the dark. 
Some stones, as if they took up light from the sun and gave it out 
again, emit a phosphorescent light after being exposed to the sun's 
rays for a time. This has often been stated to be a property of all 
diamonds, but this is not true, only certain stones exhibiting it. As 
first suggested by Kunz, it is probable that this phosphorescence is 
due to minute quantities of hydrocarbons which are heated by the 
friction given the stone. It is curious to note that the light 
is in some cases given out only from certain crystal faces. Thus 

70 



KAJPOOTANA 



SAIDARABAD 

Crolcorisdct 



Madra 

MYSORE 




Map of India, showing diamond fields. After Boutan 



diamonds are known which give out light from the cubic faces but 
not from the octahedral, while others are reported as giving out light 
of different colors from different faces. 

''The name diamond comes from the Greek adamas, which means 
unconquerable. This term was doubtless applied because of the great 
resistant power assigned to the mineral by the ancients. Besides the 
well-known tradition that it could not be broken by hammer and anvil, 
they believed that the diamond could be subdued or broken down only 
when dipped in warm goat's blood. Our words adamant and adamantine 
are also derived from adamas, the latter term still being used to describe 
the luster of the diamond. The change of adamas into the word diamond 
is thought by some to have come from prefixing to it the Italian diafano, 
transparent, in allusion to its possessing the property of transparency. 

According to classical mythology the diamond was first formed by 
Jupiter, who turned into stone a man known as Diamond of Crete, 
for refusing to forget him after he had ordered all men to do so. 
Many medicinal virtues were ascribed to the diamond, it being regarded 
as an antidote for poisons and a preventive of mania. 

The world's supply of diamonds has come almost wholly from three 
countries India, Brazil, and South Africa. Up to the beginning of the 
eighteenth century India was the only source of diamonds known. The 
diamond fields of India occur chiefly in the eastern and southern por- 
tions of the peninsula. The famed region of Golconda is in the southern 
part. This is the territory whence have come the most celebrated Indian 
stones, such as the Kohinoor and the Hope Blue. The French traveler 
Tavernier reported when he was there in 1665, that sixty thousand 
men were then employed in these mines. Now the mines have all 
been given up and the region is abandoned. 

The present yield of Indian diamonds comes almost wholly from 
mines in a district south of Allahabad and Benares. The diamonds 
occur here, as universally in India, in a conglomerate or sandstone 
made up of the remains of older rocks. 

The mines are worked almost wholly by natives of the lower caste, 
attempts of Europeans to conduct the mining not having met with 
success. The natives separate the diamonds by washing, or where the 
rock is too hard for such methods, break it up by heating and throw- 
ing cold water upon it. The production of diamonds from all of India 
is at the present time very small, not reaching a million dollars a year 
in value. It is likely in time to disappear altogether, since most of the 
old mines have been abandoned, and even their location forgotten, 
and the returns from the present mines are not very profitable. 

71 



Most of the famous large diamonds of the world have come from 
India, their origin being usually traceable to a period between the 
thirteenth and eighteenth centuries. Some of the best known of these 
are the Kohinoor, Pitt, Orloff, Great Mogul, Florentine, and Sancy. 

The Kohinoor first appeared in history in the year 1304. It was 
at that time mentioned as acquired by the Sultan Alaeddin from the 
Kajah of Malwa, in whose family it had long been held as an heir- 
loom. It was later restored to the Rajah of Gwalior; but on the 
defeat of this official, in 1526, by Humairen, emperor of Hindostan, the 
stone was presented to the latter by some of the former's adherents. Sul- 
tan Baber states that at this time the diamond was valued at " half the 
daily expense of the whole world." The stone remained in the posses- 
sion of the Mogul dynasty until the invasion of India in 1739 by 
Nadir Shah, the Persian conqueror. The reputed exclamation of the 
latter when he first saw the stone, "Koh-i-Nur!" ("Mountain of 
Light!") gave it the name by which it has since been known. 
As the reward of an alliance the diamond was given by the son 
of Nadir to Ahmed Shah, founder of the Durain Afghan empire, in 
1751. A successor of the latter sought to conceal the stone from 
a usurper by embedding it in the plaster of his cell, but after lying 
hidden in this way for many years it became exposed and was once 
more restored to the Afghan crown. An Indian prince, Runjit Singh, 
later obtained the diamond by conquest and brought it to Lahore 
where it remained until English rule was established. In 1850 it was 
sent to England in charge of two officers. It weighed at that time 
186 T Y carats. It had not a symmetrical shape, its cutting being con- 
fined, after the usual manner of Indian lapidaries, to fashioning rude 
facets on the surface. It also contained two or three flaws. In order 
to remove these, and give it a symmetrical shape, the stone was cut 
in London, in 1852, by Messrs. Coster, of Amsterdam, to the form 
of a brilliant. About 80 carats were sacrificed in this process, and 
the stone at present has a weight of 106 carats. The quality of the 
Kohinoor is not the finest, it having a slight grayish tinge; but on 
account of its romantic history it is one of the most famous, if not 
the most famous, of diamonds. 

The diamond known as the "Regent" or "Pitt" was found in 
India in 1701 by a slave, who to conceal it, cut his leg that he 
might put it in the bandage thus made necessary. He thus escaped 
with it to the coast, and offered the stone to an English skipper as 
payment for passage to a free country. The latter on receiving the 
diamond threw the slave into the sea. He then sold the gem to a dia- 

72 



mond merchant for five thousand dollars, squandered the money in 
dissipation, and went and hanged himself. The diamond was sold by 
the merchant to Sir Thomas Pitt, Governor of Fort St. George at 
Madras, for one hundred and twenty thousand dollars. When the 
latter reached England he found numerous stories afloat to the effect 
that he had obtained the gem by foul means. These reports caused 
him great distress, both because of their imputation of dishonesty and 
because of making widely known his possession of such a treasure. 
He developed a morbid fear that he would lose or be robbed of the 
gem, and while he possessed it is said never to have slept two nights 
under the same roof, and to have gone about much in disguise. During 
the stay of the stone in London it was cut into the form of a brilliant, 
the cutting reducing its weight from 410 to 136f carats. In 1717 it 
was sold to the Regent of France, Duke of Orleans, for about six hun- 
dred and seventy-five thousand dollars, which, together with what was 
received for the dust obtained in the cutting, made a profit to Pitt 
of at least five hundred thousand dollars. The diamond remained 
among the French crown jewels till 1792, when it was stolen, in com- 
pany with many other precious stones, from the Garde Meuble. Shortly 
after a note was received, evidently from the robbers, saying that the 
diamond would be found in the Alice des Veuves. In this way the 
diamond was recovered, and it has remained in the French treasury 
since. It was at one time pledged by Napoleon to the Dutch govern- 
ment as a means of securing a loan of two and a half millions of 
dollars; but aside from this, its later history seems to have been 
uneventful. It is exhibited at present in the Galerie Apollon in the 
Louvre in Paris. It is one of the purest and finest of large diamonds. 
Its present dimensions are : Length, one and one-sixth inches ; breadth, 
one inch; and thickness, three quarters of an inch. 

The Orloff diamond is to the Russian crown what the Kohinoor 
is to the British. Our first knowledge of this stone is of its forming 
one of the eyes of a Hindoo idol. How long it had glittered there 
is not known ; but its existence came to the ears of a French grenadier 
some time in the eighteenth century. This individual resolved to gain 
possession of the diamond by pretending to become a worshiper of the 
idol, and so gained the confidence of the Hindoo devotees that they 
appointed him special guardian of the god. He shortly improved 
the opportunity on a dark and stormy night to tear out the adaman- 
tine eye and escape with it to Madras. There he sold it to an 
English sea captain for ten thousand dollars and the latter to a Jew 
for sixty thousand dollars. The Jew merchant some time after brought 

73 



the stone to Amsterdam, where it was seen by Prince Orloff, of Russia, 
and purchased for the sum of four hundred and fifty thousand dollars 
in cash and an annuity of twenty thousand dollars. By Orloff the 
diamond was presented to Catherine II. of Russia, the Czarina, as 
a means of restoring him to her favor, he having forfeited this some 
time before. Catherine accepted the gift, and the diamond has remained 
among the Russian crown jewels since. It is mounted in the Imperial 
scepter, and is hence sometimes known as the " Scepter" diamond. 
It is the largest of the Indian diamonds now extant, its weight being 
193 carats. It has the shape and about the size of half a pigeon's 
egg with facets. On one surface is a V-shaped incision, and the stone 
has a slight yellow tinge. 

Our knowledge of the diamond called the " Great Mogul " is wholly 
of the past. It was described by the French traveler Tavernier, as seen 
by him in 1665 at the court of Aurung-zeb, a ruler of Hindostan. 
Tavernier gave its weight at the time he saw it as 319^ ratis, 
i.e., 280 carats; but states that it had been cut from a stone which 
weighed in the rough 787|- carats. The diamond is further described 
by him as having the form (though not the size, as often stated) 
of an egg cut in half, as being rose cut, round, and very high on one 
side, and as being of a very pure water. The subsequent history 
of the diamond is not known. Attempts have been made to identify 
it with the Kohinoor and Orloff; but in the view of Streeter, the emi- 
nent English .authority on diamonds, there is no ground for these 
views. The "Great Mogul" has probably been either wholly lost, 
or it has been cut into smaller stones. 

The "Florentine" diamond is also known as the "Austrian Yellow" 
and "Tuscan." It has a weight of 139^ carats, and is cut so as to form 
a nine-rayed star of the rose form. It is of a citron hue. Its authentic 
history is known only back to the time of Tavernier, that writer having 
seen it in the collection of the Grand Duke of Tuscany. By the latter 
it was transferred to the Empress Maria Theresa, and it has since 
remained in the possession of the royal House of Austria. It is often 
asserted to have been owned by Charles the Bold, and to have been 
lost by him on the battle-field of Nancy or Granson; but Streeter 
regards this story incorrect. 

/< The Sancy diamond was purchased in 1570 in Constantinople by 
M. de Sancy, French ambassador to the Ottoman court. On his return 
to France he permitted his sovereign, Henry IV. of Navarre, to use 
it as security for a loan, for the purpose of employing & body of Swiss 
recruits. But the messenger to whom the gem was intrusted disap- 

74 



peared on the way to accomplish his errand, and after some time it 
was learned that he had been assassinated. Confident, however, that 
he had found some way of guarding the gem, de Sancy had the body 
of the messenger disinterred,' and in his stomach the diamond was found. " 

Some time after de Sancy sold the diamond to Queen Elizabeth 
of England, and it remained in the possession of the English royal 
family until about 1695, when it was sold to Louis XIV. of France, 
for one hundred and twenty-five thousand dollars. It was stolen in 
the robbery of the Garde Meuble, but turned up about 1828, and was 
sold by a French merchant to Prince Demidoff. It then went back 
to the land of its birth, India, for it was bought by an Indian prince, 
in whose possession it either remains, or, according to some authorities, it 
is owned by a French syndicate. The Sancy is almond-shaped, facetted 
on both sides, and weighs 53^ carats. 

After those of India the Brazilian diamond-fields were the first 
important ones to become known. The date of their discovery is gen- 
erally considered to be 1729. The diamonds were first found in river 
sands which had for some time been worked for gold by adventurers 
who penetrated into the region from the coast, but who attached no 
importance to the little bright crystals sometimes seen in the bottoms 
of their gold pans. It is said that a monk who had seen diamonds 
mined in India was the first to recognize the nature of the Brazil- 
ian stones. The news of the discovery reached the Portuguese gov- 
ernment, and the king of Portugal immediately took possession of 
all lands likely to be diamondiferous, at the same time inaugurating 
a despotic rule which burdened the country for many years. The dia- 
monds at first obtained came wholly from the sands and gravels of the 
brook and river beds. These sands, universally known by the Portu- 
guese word cascalhos, still afford a large part of the supply of Brazilian 
diamonds. Extensive upland deposits are, however, now also known. 
These are called servicos do campo, while the river deposits are known 
as servicos do rio. Several provinces of Brazil afford diamonds, vi/,., 
Bahia, Goyaz, Matto Grosso, Parana, and Minas Geraes. In all these, 
except the first and last named, the mining is desultory, and consists 
simply in washing river sands by means of wooden bowls. Enough dia- 
monds are thus obtained to afford a precarious living to the fiscadores, 
as they are called, who follow this occupation. The chief diamond- 
bearing region is in the province of Minas Geraes, and the city of Dia- 
mantina is its geographical and commercial center. This city is located 
about five hundred miles from the sea coast, at the head waters of the 
Rio Jequitinhonha and Rio Doce. The valleys of these rivers are 

75 



especially rich in diamonds, and form the region which has been 
longest and most successfully worked. Here "wet diggings" are car- 
ried on in the beds of streams, laid bare by conducting the waters into 




Map of principal diamond-fields of Brazil. After Boutan 

new channels by means of flames. The work can only be carried on 
in the dry season, as in the wet season the quantity of water in the 
rivers makes them ungovernable, and sometimes even in the dry season 
it happens that a miner has barely got the artificial way constructed 

76 




iKJE 



before the waters, increased in volume, suddenly destroy it. The fall of 
water from the artificial sluice is often employed to turn a wheel to 
keep the old channel pumped dry, but little use is made of this power 
for other purposes. When the river bed has thus been laid bare, search 
is made with a long iron rod for huge pot-holes, known as caldeiros, 
which experience has shown are more likely to contain quantities of 
diamonds than the ordinary river bed. This is natural, since the 
diamonds resist longer than other stones the constant wear due to the 
whirling about of the water in the pot-holes and hence gather there. 
It is said that sometimes on removal of a little sand large aggrega- 
tions of pure diamonds are to be seen. A single small pot-hole is 
said to have yielded 8,000 carats, or about 6 pounds of diamonds. 
The caldeiros have now been nearly all dug over, however, and the 
finding of a new one is rare. The separation of the diamonds from 
the accompanying sand and gravel is usually performed by washing, 
in the manner thus described by Gorceix:* 

" The sands are placed," he says, " in portions of two hundred 
to two hundred and fifty pounds, in a kind of hod or rectangular 
trough, only three sides of which are inclosed. The hods are arranged 
by twos, fours, or sixes by the side of a trough of water about a foot 
and a half deep so that their bottoms shall be slightly inclined toward 
it. A workman standing in the trough before each hod dashes water 
upon the sand in it. The clay and the very fine sands are carried 
away and the first separation is made. The larger pieces remaining 
in the top of the sand are picked away. The diamond is to be found 
in the two upper thirds of the mass that is left, the lower part being 
nearly sterile. The washing is afterward finished in bowls a little 
deeper and a little more conical than those used by the gold-washers. 
The washer puts the sand in the bowl and fills it with water; then by 
whirling the bowl and shaking it up and down while the sand is float- 
ing around in it, and being careful to stir it from time to time with 
his hand, he determines a classification in the order of density. This 
work would be easy if he were washing gold, for that metal is heavier 
than the substances with which it occurs, and always goes to the bot- 
tom. The diamond, however, having a density only about three and 
a half times greater than that of water, not much more than that 
of quartz and tourmaline, and less than that of the oxides of iron 
and titanium, its constant companions, settles in the middle layers. 
The washer, after several rinsings, removes the upper particles, hardly 
looking at them; and when he has reached a certain level, which his 

* Popular Science Monthly, Vol. XXI., p. 616. 

77 




Preliminary concentration of diamond-bearing gravel by dashing water upon it from 
broad wooden bowls known as bateas. Near Diamantina, Brazil 




Searching washed gravel for diamonds. Near Diamantina, Brazil 

78 






skill recognizes at once, tips his bowl slightly so as to let the water 
run off in a thin film, and perceiving the glittering crystals of the 
diamond picks them out with his fingers. The vigilance of the over- 
seers must be redoubled at this stage, particularly when slaves are 
employed, for I know of nothing equal to the skill of the slaves in 
finding diamonds, except that with which they make them disappear 
if the vigilance of the superintendent is relaxed for an instant. I can- 
not describe all the artifices employed; but I should remark that since 




Agua Suja, Brazil, showing soil worked for diamonds. An example of dry diggings 

the works have become free, fraud has greatly diminished. Under the 
old rule it overtook half the diamonds in the gravels." 

This method of washing is not confined to the river sands, but 
is also used to separate the diamonds in the upland deposits. These 
upland deposits include strata of considerable extent, composed of clay 
derived from the decomposition of a coarse conglomerate. The strata 
are divisible into three distinct layers. The first, a soil cap, is some- 
what diamondiferous ; the next low^er, a clay called secundina, is regarded 
sterile, probably on account of its tenacity, which makes it almost unwash- 
able ; while the third, called taua, is the diamond layer par excellence. 
Large areas of this sort have been and are still being worked with 
more or less profitable returns, an illustration of the latter being given 
by Gorceix, who states that he knows of miners who have washed 
the cascalhos of Bagagem for twenty years without finding a single 
diamond of value. 

79 






The origin of the Brazilian diamonds is not well understood. They 
do not appear to have originated, like those of South Africa, in eruptive 
rocks, as there are little or no traces of such rocks now to be seen. 
They were formerly supposed to be constituents of a quartz schist, 
called itacolumite, from Itacolumi, a prominent mountain peak near 
Diamantina, but this is not now believed to be the case. The present 
Director of the Geological Commission of Brazil, Orville A. Derby, 
is of the opinion that the diamonds may have been formed out of the 
carbon contained in the phyllites (clay schists) of the region by the 
intrusion in them of pegmatite veins. 

The quantity of diamonds now obtained from Brazil is compara- 
tively small, the total production in 1880 being only about forty pounds 
(80,000 carats). During the past few years an extensive drought has 
prevailed in the diamond-bearing regions, which has favored search 
for the stones and increased the output. It is difficult at any time, 
however, to learn the exact production, since there is much smug- 
gling, owing to the high duty of sixteen per cent levied on exported 
diamonds. 

The largest diamond from Brazil that is now known is that called 
"Star of the South," which weighed in the rough 254.5 carats, and 
after being cut, 125 carats. This was found in 1853 by a negro slave 
woman. It was a dodecahedron, and has a peculiarity that no other 
diamond possesses, in giving off in certain lights a rose tint, although 
perfectly white itself. It was sold for one hundred and seventy-five 
thousand dollars to a Paris syndicate, which is said in turn to have 
sold it to an Indian prince. 

The next great deposit of diamonds to be found after that of Brazil, 
and by far the most important known to-day, is that of South Africa. 

The first discovery of diamonds here is to be credited, as has so often 
been true in the finding of gems, to the picking up of pretty stones 
by children. Among such pebbles gathered by a child of Daniel Jacobs, 
a Boer farmer living near the present town of Barkly West on the 
Vaal River, one was thought by John O'Reilly, a roving trader, to be 
a diamond. To test the matter he sent the stone to Dr. Atherstone, 
a mineralogist at Grahamstown, who at once identified it as a veritable 
diamond, and expressed the belief that more were likely to be found 
in the region. This find was made in 1867, but no more diamonds 
were discovered until March, 1869, when a superb stone weighing 
S3 carats, and which not long after brought a price of one hundred 
and twenty-five thousand dollars, was picked up in the same region. 
This discovery was sufficient to set a tide of diamond-seekers toward 

80 




I 



a 
w 



the valley, and soon their camps were spread all up and down the 
Vaal River. The separation of the diamonds from the gravel was 
at first performed by hand panning, after the method of the Brazilian 
and Indian miners; but after a time a piece of apparatus consisting 
of a long box with a sieve bottom, mounted so that it could be swung 
back and forth, came into use. This was called sometimes a "baby" 
and sometimes a "cradle." The meshes of the sieve were of such 
size as to allow the fine refuse to pass through, while the medium- 
sized pebbles likely to contain diamonds were retained and rolled into 
a tub. The contents of the latter after shaking were turned upon 
a "sorting table" and the diamonds picked out by careful scraping. 
By use of this apparatus a larger quantity of the gravel could be 
shaken at a time with less labor. In this way large areas of the 
gravel beds of the valley were sorted over for diamonds. It soon 
appeared, however, that though the extent of the diamond - bearing 
gravels was great in area it was small in depth, and though large 
numbers of men found profitable employment there for a time, if no 
other source of supply had appeared diamond-mining in South Africa 
would probably long ago have been a thing of the past. But in 
August, 1870, a farm overseer by the name of De Klerk, living at Ja- 
gersfontein, having learned that diamonds were usually accompanied 
in the river diggings by garnets, and having found some of the latter 
on his farm, went to work with a common wire sieve, and at a depth 
of six feet found a fine diamond of 50 carats. A month later a similar 
discovery was made at the place now called Kimberley, and further 
and deeper digging only disclosed more and more of the diamonds. 
The news of these discoveries spread rapidly, and soon the farms on 
which the diamonds had been found were staked out in claims by 
hordes of diamond diggers. The returns from the diggings proved 
profitable ; but the diamond-bearing areas were so small that the intri- 
cacy of the claims within them became a serious matter. At first roads 
were left by common consent between the claims to provide means 
of transportation and places for work, as shown in the accompanying 
view of the Kimberley mines in 1872.; but as the roads were too full 
of diamonds to be spared, they were in time cut away, and the plan 
was adopted of removing the diamond-bearing earth by means of cars 
carried by long wire ropes to the surface. Each claim or owner had 
his own system of pulleys, and the mines soon came to look as if covered 
by a vast spider's web. In ] 885, within an area of seventy acres, at Kim- 
berley forty-two companies and fifty-six private firms or individuals 
were working. As the diggings grew deeper the situation became 

81 



more and more serious because of the different depths to which differ- 
ent claims were carried. The walls of the outlying areas disintegrated 
rapidly, and fell from time to time in great masses, causing sad loss 
of life. Moreover, the immense output of diamonds, and extensive 
competition between the different producers, caused a lowering of the 
price which made it unprofitable to work many of the poorer parts 
of the mines. A consolidation of interests seemed the only way out 
of these difficulties, and this was finally accomplished under the leader- 
ship of Cecil Rhodes. In 1888 a joint stock company, known as the 
De Beers Consolidated Mines, Limited, was formed to operate the impor- 
tant diamond properties in the region of Kimberley. The workings 
of this company have proved highly satisfactory, both in promoting 
a safe and economical extraction of the diamonds and in limiting 
their output. Under the new management the system of open-cut 
workings has been abandoned in all the mines except the Premier, 
and the diamond - bearing ground is mined by a system of tunnels 
at various levels. From these it is hoisted to the surface through 
shafts, and then spread out over large areas, called floors, to disinte- 
grate. The disintegration is accomplished by exposure to sun and 
rain, huge harrows being drawn frequently over the floors to assist 
in the work. The time required for proper disintegration varies from 
three to six months according to the nature of the rock. When suffi- 
ciently disintegrated, the rock is carried to machines which wash away 
the finer particles and mechanically concentrate that of a size likely 
to contain diamonds of value. 

For a long time the diamonds were picked out from this concen- 
trate by hand, the assortment of pebbles being spread on tables and 
picked over. It has lately been found, however, as already noted, 
that by running the concentrate over percussion tables the surfaces 
of which are covered with a thick coat of grease, that the diamonds 
are caught and held by the grease while the valueless minerals pass on. 
In this way a more nearly complete as well as more rapid extrac- 
tion of the diamonds is secured than when the concentrate is sorted 
by hand. 

After being sorted out the diamonds are cleaned by boiling in a mix- 
ture of nitric and sulphuric acids, rinsing in water, and finally washing 
in alcohol. They are then assorted according to quality into about ten 
classes, ranging from the finest, called ll close goods," to the poorest, 
called " boart." The diamonds belonging to the first eight of these 
classes are then again assorted according to color, the " blue whites " 
standing first and the "yellows" last. They are then wrapped in 

82 



parcels and forwarded to London, where they are reasserted and sup- 
plied to the trade. The color, size, and quality of the diamonds from 
the different mines vary considerably, but are fairly constant for each 
mine. A majority of the diamonds from the De Beers mine, for instance, 
are "yellows," colorless stones being almost never found there. The 
Dutoitspan mine, on the other hand, produces many blue-white and 
white stones, and these are generally of large size. The iiamonds 

o */ o 

of the Jagersfontein mine excel all others in quality, superb blue-white 
stones being the rule. 

From the South African mines have been obtained the world's 
largest diamonds, unless the mythical "Grand Mogul" and question- 
able " Braganza " are to be excepted. The largest and finest of 1 the 
South African stones, also the superior of any other known diamond, 
is that called the "Jubilee" or " Excelsior." This stone weighs 239 
carats, and was cut from a crystal of 9 7 If carats found at Jagers- 
fontein in 1893. It is cut as a brilliant, and has the following dimen- 
sions: Length, If inch; breadth, If inch; depth, 1 inch. 

Other noted South African diamonds are the "Tiffany," a yellow 
diamond weighing 125^ carats; the "Star of South Africa," already 
mentioned as found in 1869, and now cut to a size of 46^ carats; 
and the "Victoria," a stone of 180 carats, cut from an octahedron 
weighing 457^ carats. 

Turning to a consideration of the geological characters of the dia- 
mond-bearing areas, it may be stated that each is approximately spheri- 
cal or oval in form, with an average diameter of two hundred to three 
hundred yards. The four principal mines are embraced within an area 
four miles square. The areas in which the diamonds were found were 
originally somewhat depressed, giving to them the name of "pans." The 
upper portion of the area was a friable mass of a yellow color called 
"yellow ground." On going deeper the color of this portion changed 
to a blue or greenish blue, and the rock became firmer. It is this 
" blue " or " blue ground " which, now that the yellow ground has 
become exhausted, furnishes all the diamonds. The strata which inclose 
it are, as illustrated in the accompanying figure, at the top, a layer of 
basalt about fifty feet in thickness ; below this two hundred to three 
hundred feet of a nearly horizontal black, carbonaceous shale; next 
a thin conglomerate; next about four hundred feet of a dark rock 
called at first melaphyre, but now regarded as olivine diabase; and 
finally a quartzite which extends as far as exploration has gone. The 
relation of the diamond-bearing ground to these strata seems to be in 
the nature of a volcanic intrusion. The diamond-bearing or " blue 

83 



ground " is a breccia, consisting largely of chrysolite more or' less altered 
to serpentine, and accompanied by bronzite, pyrope, diopside, zircon? 
cyanite, mica, pyrite, magnetite, ilmenite, and some other minerals. 
There are also fragments of shale and boulders of varying composition 
in the blue ground. 

The origin of the diamonds in the blue ground has naturally been 
the source of much speculation, but no theory meets general accept- 
ance as yet. One of the first suggestions was that of Professor Henry 
Carvill Lewis, of Philadelphia, that the heat of the volcanic intrusion 







Section of De Beers diamond mine, South Africa, showing character of strata. The "blue 

ground " is the diamond-bearing area 

transformed the carbon of the surface shales into diamond. This theory 
seems untenable, however, for many reasons, as shown by Mr. Gardner 
F. Williams in his recent work. Mr. Williams states that about the 
diamond-bearing deposits at Jagersfontein there are no such shales, 
while in the regions where they do exist there is no alteration observ- 
able at the junction of the shales and blue ground, nor among the 
fragments of shale inclosed in the blue. According to another theory 
the blue ground is not of igneous origin, but is a sort of mud forced 
up by hydrostatic pressure. This brought up the diamonds from depths 
below. The present trend of opinion seems to be that the origin of the 
diamond was deep-seated; but whether its matrix was the basic rock 
in which it is now found or some other is not known. Professor 
T. G. Bonney, who has given much attention to the matter, , is of the 

84 



opinion that the diamonds were originally connected with eclogite, 
a metamorphic rock carrying somewhat more silica than character- 
izes the present blue ground, and containing considerable garnet. 

About ninety-five per cent of the world's supply of diamonds comes 
at the present time from the South African mines, their annual pro- 
duction being about 2,500,000 carats. Other countries which produce 
small quantities of diamonds, besides those already mentioned, are 
Borneo, Australia, British Guiana, and the United States. 

The diamonds of Borneo come from two portions of the island, 
one field being in the western and the other in the southern part. 
These fields have been known and worked from time immemorial; 
but have afforded only a small supply, the product varying from 
tw r o thousand to six thousand carats annually. In the western part 
of the island the diamonds occur in alluvial gravels, and their parent 
rock is not known. In the southern part they occur in a conglomer- 
ate overlying strata of Eocene age. The majority of the diamonds 
obtained are small and of rather poor quality. Their mining is per- 
formed in a desultory way by native Malays and Chinese, and the 
supply seems gradually to be decreasing. 

The first discovery of diamonds in Australia was made in 1851 in 
placer gold-mining in New South Wales. The locality was not far 
from Bathurst. Since then in this locality, and the neighboring head 
waters of the Macquarie River, a number of small diamonds have been 
found. The largest number were found along the Cudgegong River, 
northwest of Mudgee, in an old river drift covered with basalt. About 
2,500 stones were obtained there in 1869. Accompanying the dia- 
monds are gold, garnet, zircon, tinstone, or cassiterite, tourmaline, and 
magnetite. The gold and diamonds are obtained as in California by 
tunneling under, the basalt so as to excavate the gravels. Another 
locality in New South Wales which has yielded diamonds is in the 
vicinity of Bingera. Here the diamonds occur in gold and ruby-bearing 
sands, the accompanying minerals being quite similar to those men- 
tioned above. 

In Southern and Western Australia and in Tasmania a few dia- 
monds have also been found. The Australian diamonds are all small, 
none of over 6 carats weight being known. The yield from New South 
Wales in 1899 was reported to be 25,874 carats. 

Small diamonds have been found at several points in the Ural Moun- 
tains. The first were obtained about 1829 in the vicinity of Bissersk, 
Government of Perm, occurring in alluvial sands with gold, platinum, 
quartz, magnetite, and anatase. It is said that Alexander Humboldt 

85 



predicted the finding of diamonds here from the similarity of the 
gravels to those of Brazil in which diamonds are obtained. 

Later finds of diamonds have been made near Ekaterinburg and 
in Werchne Uralsk and Troitzk in the Government of Orenburg; 
likewise in connection with auriferous sands. 

Diamonds have also been found in Lapland in the vicinity of Var- 
anger Fjord on the Arctic Sea. They occur in river sands, together 
with garnet, quartz, rutile, and other minerals usually found accom- 
panying diamond. These diamonds are small and scarce. 

British Guiana has recently come into prominence as a field which 
may produce a profitable supply of diamonds. Small stones were first 
found here about 1890, and work has been continued until now a con- 
siderable amount of mining is carried on. The locality is along the 
Upper Mazaruni River, two hundred and fifty miles south of the town 
of Bartica. The journey to it is a long and difficult one, all supplies 
requiring to be transported over a narrow trail through a tropical 
jungle. The diamonds occur in a formation of sandy clay with other 
pebbles and ironstone nodules. They are separated by washing the clay 
in sieves of one-sixteenth inch mesh to remove the fine particles, and 
are then picked out by hand. The yield is quite remunerative, nine 
men having in one instance obtained four hundred stones by working 
eighteen days. The stones are small in size, few being above two carats 
weight, but they are of good quality. Several companies have been 
organized to work the deposits, and a measurable output is likely to be 
obtained. 

The occurrence of diamonds in the United States is largely confined 
to two regions ; the first a belt of country lying along the eastern base 
of the southern Alleghanies from Virginia to Georgia, while the other 
extends along the western base of the Sierra Nevada and Cascade 
ranges in northern California and southern Oregon. There is also 
a third, of less importance, belonging to the Kettle moraine district 
of southern Wisconsin. One of the diamonds found in the southern 
Alleghanies weighed 23f carats. It was found in 1855 at Manchester, 
Virginia, and is usually known as the Dewey diamond from the name 
of its one-time owner. Eight or ten diamonds, varying from one to four 
carats in weight, have been found in various localities in North Carolina ; 
ten or twelve counties in Georgia have furnished one or more small 
stones, and one or two are reported from South Carolina. These dia- 
monds have all been found loose in gravels, and have been obtained 
either while washing the gravels for gold, or in digging wells, or they 
have been picked up by children. A resemblance of certain strata in 




GLACIAL MAP OF THE GREAT LAKES REGION. 



M!orai.n.a. 
Diamond Localities 



Ol.de IT Dvi I L. 

X ^ 
Glaoial Striae . 



Newer- Drii t 

Ti-a.cls.oE Diai-n.oi-vd6. 
El, Eagle. O, Oregon, 
i-ii Cvlf.. B Surlin.(i,toi-L 



North Carolina to the itacohnnite of Brazil, in which diamonds are 
found, has at times been urged as indicating that these may have 
been the source of the diamonds, but no discovery of such stones has 
yet been made in this formation. The diamonds of the Kettle moraine 
region of southern Wisconsin have all been discovered since 1876. 
They have been obtained at six localities in Wisconsin, and one locality 
each in Michigan and Ohio. Seven good-sized diamonds have been found, 
the largest weighing 21^ carats, and one locality has yielded numerous 
small stones. The diamonds were obtained in gravels of glacial origin, 
and Hobbs has shown, from a study of the directions of glacial move- 
ment, that the original source of the gems may have been the territory 
lying southwest and south of Hudson's Bay. The localities where the 
diamonds were found, and the probable course of their distribution 
southward, are shown on the accompanying map. 

The diamonds of California have been found in connection with . 
gold-bearing gravels, the gravels being sometimes those buried under 
lava flows. In Amador, Butte, El Dorado, Nevada, and Trinity counties 
diamonds have been found, the stones rarely exceeding two carats in 
weight, but being generally of excellent quality. The accompanying 
minerals have been zircon, topaz, quartz, epidote, pyrite, chromite, etc. 
The diamonds are discovered in washing for gold; but the yield has 
never been sufficient to repay search for them alone, nor is it likely 
ever to be. In one or two localities in Oregon, Idaho, and Montana 
diamonds have been similarly obtained. 

Numerous attempts have been made to produce the diamond artifi- 
cially, some of which have been attended with success, although no stones 
large enough for industrial or ornamental use have yet been made. 

Moissan, of Paris, in 1893 succeeded in producing diamonds by heat- 
ing iron saturated with carbon to a high temperature, and then sud- 
denly cooling the exterior of the mass. This exterior cooling caused 
an intense pressure on the interior, whence black diamonds of micro- 
scopic size were produced as a result of the heat and pressure, as it 
is believed. 

Still more recently, von Hasslinger has obtained diamonds by fusing 
a mixture corresponding in composition to the South African diamond- 
bearing breccias. The diamonds were small, not exceeding .002 of an 
inch in diameter, but they were colorless and transparent crystals. 
The success of these experiments gives some reason to believe that 
fair-sized diamonds may in time be produced artificially. 



87 



CORUNDUM 

(RUBY, SAPPHIRE, ETC.) 

The mineral species corundum affords a number of gems known by 
different names because the stones were used as gems before their miner- 
alogical identity was discovered. Thus the ruby is red corundum and 
sapphire blue corundum. When corundum suitable for gem purposes 
occurs of other colors, such as green, yellow, or violet, the gems are 
sometimes known as green, yellow, or violet sapphires, respectively, 
or by the name of another gem which they closely resemble in color, 
with the adjective "Oriental" prefixed. Such are the gems known 
as Oriental topaz, Oriental emerald, Oriental aquamarine, Oriental hya- 
cinth, Oriental amethyst, and Oriental chrysolite. Colorless corundum 
is known as leucosapphire. While corundum of all colors is used for 
gems, it is only that which is transparent which can be so employed. 
This is sometimes called noble corundum to distinguish it from common 
corundum. The two, however, often occur together. Common corundum 
is used as an abrasive, emery being one of its varieties, but it has no 
gem value. 

Corundum is a sesquioxide of aluminum, with the percentages, alumina 
53.2, oxygen 46.8. Its hardness is 9 in the scale, and no mineral except 
the diamond equals it in this respect. This hardness gives it a wear- 
ing quality as a gem second only to the diamond. The varieties 
of corundum differ slightly in hardness, sapphire being the hardest. 
Noble corundum has a brilliant, vitreous luster, which, while not equal 
to that of the diamond, is superior to that exhibited by almost any 
other gem. Corundum is a heavy mineral, its specific gravity being 
four times that of water. This high specific gravity affords an easy 
means of distinguishing gems of corundum from those of other species. 
Corundum is infusible, and is not attacked by acids. It crystallizes in 
the rhombohedral division of the hexagonal system, certain crystal forms 
being characteristic of the two varieties, ruby and sapphire. Thus ruby 
tends to crystallize in flat rhombohedral crystals, while sapphire generally 
forms in longer hexagonal prisms. (See colored plate.) Corundum 
is doubly refracting and dichroic. Of the different colors of corundum 
above referred to, the blue or sapphire is most common, the red or ruby 

88 



next. The other colors occur rather sparingly, green having been almost 
unknown until the discovery of the Montana sapphires. The nature of 
the coloring ingredient of the different varieties of corundum is not 
known, but there is some reason for believing it to be chromium, for 
Fremy obtained artificial red and blue corundum by mixing chromium 
with his other ingredients, after many other attempts to obtain the 
desired color had failed. 

Red corundum varies in hue from rose to deep red. That of the 
latter tint is the true ruby, the color known as pigeon's blood being most 
highly prized. Faultless stones of this color have long been the most 
valuable of gems, exceeding the diamond in price, weight for weight. 
At the present time they are worth between $2,000 and $3,000 per 
carat. The writer recently saw a ruby of nine carats in the possession 
of a Chicago jeweler which is valued at $25,000, and one of eleven 
carats is reported to have been lately sold for $80,000. But few rubies 
exceeding ten carats are known. The King of Pegu is reported to have 
one the size of a hen's egg, but as no one has ever seen it the story 
may well be doubted. In the crown of the Empress Catherine was, how- 
ever, one the size of a pigeon's egg. There is also a large uncut ruby in 
the British crown, said to have been given to Edward, Prince of Wales, 
by the King of Castile, in 1367. Ruskin calls it the loveliest precious 
stone of which he has any knowledge. This is probably, however, a 
spinel ruby, not a corundum ruby. 

The chief home of the true ruby is Burmah. From its mines and 
those of Siam and Ceylon have come practically all the world's supply. 
The most important Burmese mines are in Mogouk, ninety miles north 
of Mandalay. The rubies were evidently formed here in limestone, which 
is now much decomposed, and seem to have been the result of metamor- 
phism of the limestone by the entrance of eruptive rocks. The ruby- 
bearing earth is known as " by on," and the gems are obtained from 
it by washing. They are usually in the form of more or less complete 
crystals. The mines have been worked since the British occupation 
of Burmah in 1886, by a British company, and there can be little doubt 
that a desire to acquire these mines was one reason for the occupation. 
The mines have not proved very profitable, however, and only within the 
last year or two has the company been able to pay any dividends. The 
hope of success has lain in the introduction of machinery for washing 
the byon more cheaply than it could be done by the primitive native 
methods, and it is now believed by the introduction of an electrical 
power plant that this has been accomplished. This company now pro- 
duces at least one-half the annual yield of rubies of the world. 

89 





Bed of ruby-bearing gravel at Caler Fork, Cowee Valley, Macon County, North Carolina 




Washing gravel for rubies, Cowee Valley, Macon County, North Carolina 

90 



Previous to the working of the mines by the English the mining 
was performed by domestic labor under control of the native govern- 
ment, all rubies above a certain size going to the king. Whenever 
a ruby of unusual size was found a procession of grandees, with soldiers 
and elephants, was sent out to meet it. One of the titles of the King 
of Burmah was Lord of the Rubies. 

-The Siamese rubies come from near Bangkok, on the Gulf of Siam. 
They occur in a clay which seems to be the product of alteration of a 
basalt. These rubies are not equal in quality to those of Burmah. 
Rubies are also found in the gem gravels of Ceylon, and in Afghanistan, 
thirty-two miles east of Cabul. 

In our own country ruby corundum is occasionally found in connec- 
tion with opaque corundum in Macon County, North Carolina. In the 
gravels of Caler Fork of Cowee Creek of this county good rubies are 
found in sufficient quantity to reward systematic mining for them. 
They are known as "Cowee Creek" rubies. 

The gravels containing them are " washed" by methods described by 
Dr. J. H. Pratt as similar to those used in the West for washing gold- 
bearing gravels. Both the gravel and the soil which overlies it are 
washed into a line of sluice boxes which lead into a sieve box. From 
the latter the dirt and fine gravel are. washed away. The material that 
remains is shoveled into a rocker, into the bottom of which the rubies, 
being heavier, gradually work, and are then removed by hand picking. 
These rubies are mostly small, but some gems of three or four carats' 
weight and of excellent color have been obtained. 

Among the Montana sapphires an occasional red stone is found, but 
they do not have the choicest red color. 

Another source of rubies is their artificial production, after the method 
discovered by the French chemist Fremy. The artificial rubies are made 
by heating a mixture of aluminum sesquioxide, carbonate of lime, barium 
fluoride, and potassium chromate in a porous clay crucible to a tem- 
perature of 1500 C., and keeping the mixture fluid for eight days. 
Well -formed, clear crystals up to one -third of a carat in weight 
tre thus produced, which have the hardness and color of native ruby. 
They are not considered so valuable as gems as the latter, and can 
usually be distinguished by the minute air bubbles which they contain. 
The expense of making them is nearly equal to the value of native 
rubies, so that their production is likely to be limited. 

Other substitutes for the ruby are garnet, that from South Africa 
being known as Cape ruby, hyacinth, red tourmaline, known as Siberian 
ruby, rose topaz, sometimes known as Brazilian ruby, and spinel. None 

91 



of these is as hard as the ruby, and each differs sufficiently from the 
ruby in its refractive powers, or specific gravity, to make distinc- 
tion easy. 

Rubies were known to the ancients, being mentioned in the Bible in 
Proverbs and Job. The Greeks and Romans ascribed to the ruby the 
power of giving light in the dark, and the Hindoos describe the abodes 
of their gods as thus lighted. The ruby was much worn as an amulet, 
being supposed to protect the wearer against plague, poison, and evil 
spirits. It was also thought that it would turn dark if its owner 
were in danger, and would not regain its color until the peril was 
over. The Burmese believe that the ruby ripens like fruit. The crude 
are colorless; thence they grade yellow, green, blue, red. 

The ruby is usually cut in the form of the brilliant, like the dia- 
mond, but sometimes the step cut is advantageously employed. The 
native gem -cutters of India do not cut facets on their rubies, but 
simply round and polish them. 

Blue, precious corundum, or sapphire, is more abundant than the 
red or ruby. Like the red, the blue color seems to be due to a con- 
tent of chromium, since in the artificial crystals already mentioned 
as produced by Fremy, both colors occur at times in the same crystal. 
This occurrence of two colors in single crystals is also found in 
Nature, some being red at one end and blue at the other; or, perhaps 
what is more frequent, the center of the crystal may be yellow and 
the exterior blue. This coloring is not uncommon among the Australian 
sapphires, and unique gems are obtained by cutting them so as to show 
the two colors. Bauer describes a figure of Confucius carved from 
a sapphire, of which the head is white, the trunk and arms blue, and 
the legs yellow. The color of sapphire most highly prized is that 
known as cornflower-blue. The cornflower (Centaurea cyanus) is also 
known in this country by the name of " bachelor's button," and excel- 
lently typifies the true sapphire color. Other shades of blue which 
occur in the sapphire, are indigo-blue, smalt-blue, berlin-blue, and 
greenish and grayish blues. The sapphires of darker colors are usually 
known as male and those of lighter colors as female sapphires. In 
addition to possessing the true corn-flower blue color, the best sapphires 
should exhibit a velvety sheen, the value of the stone being greater 
the more perfect this character. 

As already noted, sapphire is somewhat harder than ruby, and it 
is also somewhat heavier. The Montana sapphires are said to be espe- 
cially hard. 

Sapphires have at the present time not over half the value of a ruby 

92 




Corundum mine from which some sapphire is obtained 
Corundum Hill, Macon County, North Carolina 



of the same size. A price of forty dollars per carat is an average one 
for a small stone; and as much larger stones are comparatively 
common, the price does not increase so rapidly as does that of the 
ruby with an increase in size. 

The world's supply of sapphires comes chiefly from Siam. The most 
important mines of that country are those of Battambong, a city south- 
east of Bangkok. The sapphires occur in a sandy clay, out of which 
they are washed. The sapphire-bearing region is about a hundred miles 
in length. Together with the sapphires occur some rubies, especially 
in the southern part of the district. Sapphires also occur among the 
rubies of Bur mail, but in small numbers. The so-called gem gravels 
of Ceylon furnish many sapphires, though their quality is not equal 
to those of Siam, because of paleness of color. 

Another locality for sapphires, discovered about 1882, is Banskar, 
in Cashmere, India. These stones were first disclosed by the fall of an 
avalanche, and later were discovered to exist in the region in consider- 
able numbers. For a time they could be cheaply purchased, but are 
now jealously guarded by the government. 

The Montana sapphires have been known since 1865, but were not 
systematically worked until 1891. They occur in river sands east 
of Helena, and were first obtained in washing for gold. Now the 
mother rock has been discovered; and this is mined, the rock being 
taken out, piled in heaps, and submitted to the action of frost through 
the winter. The sapphires thus become loosened and can be readily 
separated. These sapphires are well crystallized and are of good aver- 
age size, though few gems exceed six carats in weight. Their luster 
and color are for the most part of first quality, and the stones are in 
demand for the best of jewelry. The most recent find of sapphires 
has been in Central Queensland, Australia, at a place called "^Anakie, 
twenty -six miles west of Emerald. Here sapphires occur over an 
extensive area. Green, yellow, pale blue, and dark blue stones are 
those most commonly found, the cornflower-blue occurring but rarely. 
Hence, the stones have not been widely used as yet. They reach sizes 
of from thirty to fifty carats. 

The common corundum of North Carolina, mined extensively as an 
abrasive, often also contains blue transparent portions from which gems 
can be made. One of the best known mines yielding such stones is that 
at Corundum Hill, in Macon County. This also produces a few rubies, 
and a fine specimen of Oriental emerald, or green sapphire, was obtained 
here. This was a crystal 4 by 2 by 1 3- inches, which would afford 
several first-class gems. 



Noble corundum of other colors than those of blue and red is not 
of abundant occurrence, nor is it ordinarily as highly prized as are 
the sapphire and ruby. Colorless sapphire, or leucosapphire, is some- 
times used as a substitute for the diamond, from which it can readily 
be distinguished by its lower hardness and higher specific gravity. 

Certain specimens of both sapphire and ruby, but especially the 
former, exhibit when polished a six-rayed star. This appears as beams 
of light, radiating from a center which changes in position as the stone 
is turned. Such stones are called star, or asteriated sapphires, or rubies, 
and are highly prized. They are usually cut with rounded surface, 
as this best brings out the figure. The cause of the star-shaped figure 
is generally supposed to be the total reflection of light from countless 
microscopic cavities in the stone, which are arranged parallel to the 
faces of a six-sided prism. Some authorities believe, however, that mul- 
titudes of twining lamellae similarly arranged cause the appearance. 

Burton, the African traveler, is said always to have carried a star 
sapphire about with him, as a means of winning respect from the 
barbarous peoples among whom he journeyed. The savages believed 
that the stone must be a talisman of great power and feared to incur 
its owner's enmity. 

Sapphire is a word which is the same in nearly all languages, 
a fact which testifies to the ancient use of the stone. In Chaldean, 
Hebrew, Greek, and Latin the word has the same form as in mod- 
ern tongues. In early times sapphire was believed to be a destroyer 
of poison, so that if put into a glass with a spider or venomous reptile 
it would kill it. It was regarded also as a remedy against fevers 
if placed on the heart, or soaked in vinegar and the extract admin- 
istered. The wearer of a sapphire was rendered by it chaste, virtuous, 
pious, devout, and wise. 



SPINEL 

(RUBY SPINEL, BALAS RUBY) 

The group of spinel includes in mineralogy a number of species of 
different though analogous composition. The spinel employed as a gem 
is almost wholly a magnesium aluminate, having the percentage composi- 
tion: alumina 71.8 and magnesia 28.2. This is usually of a red color, 
different shades giving gems known by different names as follows : Deep 
red, spinel-ruby; rose-red, balas ruby; yellow or orange red, rubicelle; 
violet-red, almandine ruby. Spinel is thus known among gems chiefly 
as a relative of the ruby, and this sort of spinel will first be con- 
sidered. 

The spinel rubies differ from the true or corundum rubies in hard- 
ness, specific gravity, and system of crystallization. The hardness of 
spinel is 8, or about that of topaz, and the specific gravity 3.6. It is 
thus neither as hard nor as heavy as corundum ruby. Again, the system 
of crystallization differs. Spinel crystallizes in the isometric system, and 
is usually found in the form of octahedrons, while corundum ruby is 
hexagonal in crystallization. (See colored plate.) Spinel is singly refract- 
ing in polarized light, and corundum doubly refracting. Spinel ruby is 
infusible before the blowpipe, but on heating undergoes a curious series 
of changes in color which are quite characteristic. The red changes 
first to brown, and then becomes black and opaque, but on cooling the 
black changes to green, then becomes nearly colorless, and finally the 
stone resumes its original red color. As a small percentage of chro- 
mium is usually found by analysis to exist in ruby spinel, its color is 
generally considered to be due to this ingredient. While the spinel ruby 
is considered of less value than the corundum ruby, and is sometimes by 
fraud or error substituted for the latter, it yet has a definite value as a 
gem when sold under the name of spinel ruby or some of its varieties. 
This value is usually reckoned at about half that of the corundum ruby, 
although variations in quality of the stones, as well as changes in demand, 
cause differences of price. Thus Emanuel mentions a spinel ruby of good 
quality weighing 40 carats, which in 1856 was sold for $2,000, but 
in 1862 brought at public auction only $400. In 1866, however, it was 
again sold for $1,200. A spinel ruby among the French crown jewels, 

95 



weighing 56 carats, was in 1791 valued at $10,000. This is much more 
than such a stone would now probably be worth. 

Not only is spinel ruby related to corundum ruby in color and use, 
but the two are frequently associated together in nature. The gem 
gravels of Ceylon, Siam, Australia, and Brazil contain both kinds of 
rubies, and the ruby mines of Upper Burmah, where the corundum ruby 
occurs in a crystalline limestone, produce also large quantities of spinel 
rubies. Spinel rubies also come in large quantity from 'Badakschan, in 
Afghanistan, near the river Oxus, the name of balas rubies, by which 
they are often known, being said to be derived from Beloochistan, 
another form of which word is Balakschan. The Persians have a tradi- 
tion regarding these mines, that they were disclosed by an earthquake 
which rent the mountain in twain. 

The localities above mentioned furnish nearly all the spinel rubies 
of commerce. A few have been found in North America, Hamburgh, 
New Jersey, and San Luis Obispo, California, being two localities where 
small crystals have been obtained, but they have never afforded any 
appreciable supply. No spinel rubies of great size are known. Bauer 
mentions as the largest known, two cut stones, one of 81 carats, and 
the other 72^ carats, exhibited at the London Exposition of 1862. The 
King of Oude is said at one time to have possessed a spinel ruby the size 
of a pigeon's egg. Another celebrated spinel ruby is that known as the 
' Ruby of the Black Prince," which is shown among the English crown 
jewels in the Tower of London. 

Spinel occurs in many other colors besides red, such as orange, green, 
blue, and indigo, as well as white and black. Occasionally colorless 
spinels occur, and as they cannot be distinguished by their behavior in 
polarized light from the diamond, it is sometimes sought to substitute 
them for the latter. They can be detected at once, however, by their 
inferior hardness. While spinels of any color, if transparent and free 
from flaws, make desirable gems, the only colors found in sufficient quan- 
tity outside of the red to make an appreciable supply are the blue and the 
black. The blue spinels resemble the sapphire in color, though they are 
somewhat paler. They come chiefly from Ceylon and Burmah, where 
they occur together with the ruby spinel. The black spinel is known as 
ceylonite, or pleonaste, and is also obtained chiefly from Ceylon, although 
occurring of a quality suitable for cutting at Mount Vesuvius in Italy. 

Like the ruby, spinel can be made artificially, the process being to 
heat a mixture of alumina and magnesia with boracic acid, and if a red 
color is desired, a little chromium oxide. No attempt seems to have been 
made as yet, however, to manufacture it for gem purposes. 

96 



The spinel ruby seems to have been known to the ancients equally 
with the corundum ruby, and the two were probably often confounded. 
The natives of India call the spinel the pomegranate ruby, and believe 
to this day that it possesses valuable medicinal properties. 

In the Middle Ages it was believed that if one touched with this 
gem the four corners of a house, orchard, or vineyard they would be 
protected from lightning, storms, and blight. 

The Arabs had a tradition that sea cows gathered spinels from the 
Kokaf Mountains, and left them on the ground in Ceylon. Stone-gath- 
erers would then throw lumps of clay over the gems, and leave them 
until the cows, " disappointed at not finding the stones, and fretting and 
fuming with rage," returned to the sea, when their human rivals would 
come and get the stones. 



97 



BERYL 

(EMERALD, AQUAMARINE, ETC.) 

This mineral species includes a number of varieties which are highly 
valued as gems. These are, besides beryl itself, the gems emerald, 
aquamarine, and golden beryl. Of these, emerald is dark-green beryl, 
aquamarine bluish-green, or greenish-blue beryl, and golden beryl, 
yellow beryl. . Chrysoberyl is not a variety of beryl. 

While these varieties of beryl all differ in color, they are the same 
mineral, and are practically identical in composition, hardness, and other 
properties. In composition, they are a silicate of aluminum and glucinum, 
the percentages being, for normal beryl: 67 per cent of silica, 19 per cent 
of alumina, and 14 per cent of glucina. 

The beautiful green color of the emerald is probably due to a small 
quantity of chromium which it usually contains, though some authori- 
ties believe organic matter to be the coloring ingredient. To what 
substance the other varieties of the species owe their color is not 
known. 

In hardness the varieties of beryl differ little from quartz, the hard- 
ness being 7.5 to 8. They are somewhat inferior, therefore, to such 
gems as topaz, sapphire, and ruby in wearing qualities, although hard 
enough for ordinary purposes. 

The specific gravity of beryl is also about like that of quartz, 
ranging from 2.63 to 2.80. It is, therefore, relatively light as com- 
pared with other gems. Beryl is practically infusible, and is not attacked 
by acids. 

Beryl crystallizes in the hexagonal system. It usually occurs as 
six-sided prisms, commonly terminated by a single flat plane, but some- 
times by numerous small planes, giving a rounded effect, and occasion- 
ally by pyramidal planes, which cause the prism to taper to a sharp 
point. 

The crystals sometimes grow to enormous size, exceeding those 
of any other known mineral. Thus, one found in Grafton, New Hamp- 
shire, was four and one-quarter feet in length, and weighed two thou- 
sand nine hundred pounds. Another in the same locality is estimated 
to weigh two and one-half tons. In the Museum of the Boston Society 




437 



I Golden Beryl (Siberia). 
Blue Beryl (Siberia). 



BERYL. 

3 Blue Bervl 'Albany, Maine). 
4- Aquamarine (Conn.) 
' Golden Beryl (Conn.) 



copymsHT ioi, sr . w. MUMFOHO, 
lp Aquamarine (Ural Mountains). 
"I ^nit-raid i" matrix (Ural Mountains) 



or 
UN/VE 



Crystal forms of beryl 



of Natural History, and in the United States National Museum, are 
exhibited single crystals also of great size. That in Boston is three 
and one-half feet long by three feet wide, and weighs several tons. 
That in the National Muse- 
um weighs over six hundred 
pounds. 

None of these crystals is 
of a high degree of purity or 
transparency, but the crystal 
planes, at least of the prisms, 
are well developed. 

Beryl crystals have no 
marked cleavage, except a slight one parallel with the base. Where 
broken, the surface shows conchoidal fracture. 

The mineral is quite brittle. Some emeralds even have the annoy- 
ing habit of breaking of their own accord soon after removal from 
the mine. This can be prevented by warming them gradually before 
exposing them to the heat of the sun, or other sudden heat. 

Beryl and its varieties are dichroic ; i. e., the stones exhibit different 
colors when viewed in different directions. This dichroism can some- 
times be observed by the naked eye, but better with the dichroscope. 
With this instrument the twin colors seen are, for the emerald, yellowish 
green and bluish-green; for the aquamarine, straw-white and gray- 
blue; and for noble beryl, sea-green and azure. The dichroism when 
seen furnishes a positive means of distinguishing a true stone from any 
glass imitations. 

The varieties of beryl have not the brilliancy of the diamond, the 
double refraction being weak and the dispersion small. They therefore 
depend on their body colors and their luster for their beauty and attrac- 
tiveness. Fortunately they usually exhibit these qualities as well by 
artificial light as by daylight. 

Ordinary beryl is a mineral of comparatively common occurrence, 
being often found in granitic and metamorphic rocks, although that of 
common occurrence is usually too 'clouded and fractured to be of use for 
gem-cutting. There are many localities, however, where beryls of gem 
quality occur. 

Of the different varieties of beryl, the emerald is by far the most 
important as a gem. Its pure green color, unalloyed by a single ray 
of yellow, has ever made it an object to be sought for with avidity, 
and it will probably always be the standard green gem. 

The finest emeralds in the world come from Muso, a locality in the 



United States of Colombia, seventy-five miles north-northwest of Bogota. 
It is a somewhat inaccessible region, and the mining of the gems is 
a precarious occupation. The emeralds occur in a dark, bituminous lime- 
stone, which is shown by fossils to be of Cretaceous age. As emeralds 
in other localities occur only in eruptive or metamorphic rocks, it seems 
possible that the Muso emeralds have washed in from an older forma- 
tion. The emerald-bearing beds are horizontal, overlying red sandstone 
and clay slate. Calcite, quartz, pyrite, and the rare mineral parisite are 
other minerals found associated with the emerald. The manner of work- 
ing these emerald mines is thus described by Streeter : 

"The mine is worked by a company, who pay an annual rent for 
it to the government, and employ one hundred and twenty workmen. 
It has the form of a tunnel, of about one hundred yards deep, with 
very inclined walls. On the summit of the mountains, and quite near 
to the mouth of the mine, are large lakes, whose waters are shut 
off by means of water-gates, which can be easily shifted when the 
laborers require water. When the waters are freed they rush with 
great rapidity down the walls of the mine, and on reaching the bottom 
of it they are conducted by means of an underground canal through 
the mountain into a basin. To obtain the emeralds the workmen begin 
by cutting steps on the inclined walls of the mine, in order to make 
firm resting-places for their feet. The overseer places the men at cer- 
tain distances from each other to cut out wide steps with the help 
of pickaxes. The loosened stones fall by their own weight to the 
bottom of the mine. When this begins to fill, a sign is given to let 
the waters loose, which rush down with great vehemence, carrying the 
fragments of rock with them through the mountain into the basin. 
This operation is repeated until the horizontal beds are exposed in 
which the emeralds are found." 

The mines are owned by the government, by whom they are leased 
for terms of seven to fifteen years to the highest bidder. The working 
of the mines has been almost continuous since 1558, and they have been 
the principal source of emeralds obtained in modern times. Emeralds 
also occur in small numbers throughout the black aluminous schists 
of the Eastern Cordilleras of Colombia. A few are thus obtained from 
Cozenez, Somondose, Nemocon, etc. They are not mined systematically 
except at Cozenez. 

The next most prominent locality whence gem emeralds are obtained 
is in Siberia, on the river Takovaya, forty-five miles east of Ekaterinburg. 
The emeralds here found are often larger than any yet obtained in 
South America, but they are not of so good quality. They occur in 

100 



mica schist (see colored plate), and often associated with phenacite, 
chrysoberyl, rutile, etc. 

Other localities whence emeralds are obtained are Upper Egypt 
(the source of those known to the ancients) ; the Heubachthal in 
Austria; and Alexander County, North Carolina, in our own country. 
The latter locality has afforded a number of fine crystals, and work 
at the mines has recently been renewed. 

The form of cutting given the emerald depends upon the shape of 
the rough stone. The table cut like that of the emerald shown in the 
frontispiece to this work is perhaps the most common. The step cut is 
also employed, and brilliants and rose cuts are occasionally made. 

Emeralds seem to have been known and prized from the earliest 
times. They are mentioned in the Bible in several places, and their use 
in Egypt dates back to an unrecorded past, for they frequently appear 
in the ornaments found upon mummies. Readers of Roman history 
will remember that the EmperoikNero used an emerald constantly as an 
eye-glass, though whether this was a real emerald may be questioned. 

The Incas, Aztecs, and other highly civilized peoples of South America 
were reported to have used these gems profusely for purposes of adorn- 
ment and for votive-offerings. It was partly the desire to secure emeralds 
which led Cortez and his followers, early in the sixteenth century, to 
undertake the conquest of Peru. Some of the emeralds thus obtained 
from the Incas by Cortez and brought to Spain were said to have 
been marvels of the lapidary's art. One was carved into the form 
of a rose, another that of a fish with golden eyes, and another that 
of a bell with a pearl for a clapper. During the years following Cortez' 
conquest large quantities of the so-called emeralds were brought to Europe. 
Joseph d'Acosta, a traveler of the period, says the ship in which he 
returned from America to Spain carried two chests, each of which con- 
tained one hundred pounds' weight of fine emeralds. It is probably, 
however, quite incorrect to regard the stones as true emeralds. They 
were more likely jade or some other green stone to which the name 
emerald was applied. The true emerald is too brittle to be easily en- 
graved, and it is not likely that any such large quantity as reported 
was ever found of this stone. Working of the Colombian mines was 
begun by the Spaniards in 1558, and there has been practically no 
interruption in their operation since that time. 

The ancients had many superstitions regarding the emerald, one 
being that it had a power to cure diseases of the eye. Engravers of gems 
and other artificers were accustomed, therefore, to keep an emerald in 

front of them while at work, believing it would rest their eyes to look 

101 



upon it occasionally, and that the water in which the stone stood would 
cure inflammation of those organs. Another notion was that the emerald 
would reveal the inconstancy of lovers by changing color. 

"It is a gem that hath the power to show 
If plighted lovers keep their troth or no; 
If faithful, it is like the leaves of spring; 
If faithless, like those leaves when withering." 

Another belief was that the emerald would blind the eyes of the ser- 
pent, a fancy referred to in Moore's lines : 

"Blinded like serpents when they gaze 
Upon the emerald's virgin blaze." 

The emerald was also the symbol of immortality and of conquered 
sin and trial. It was believed that emeralds came from the home of the 
griffin, and that to obtain them thence exposed the miner to great danger. 

As late as the seventeenth century powdered emerald was widely 
used as a drug, being regarded when taken internally as a powerful 
remedy for dysentery, epilepsy, venomous bites, and fevers. 

Like all other gems, the value of emeralds varies much according 
to their perfection. Those of the best grade are worth from $100 to 
$1,000 a carat. The passion for emeralds at the present time, together 
with the fact that very few are being found, makes them among the 
most costly of gems. A three-carat emerald recently sold for $875, 
and a six-carat stone for $4,000. A six-carat diamond might not be 
worth over $1,000 at present. The color should be a dark velvety 
green, those of lighter shades being much less valuable. Owing to the 
extreme brittleness of the mineral, emeralds usually contain flaws, so 
that " an emerald without a flaw " has passed into a proverb to indicate 
a thing almost unattainable. 

The largest and most beautiful emerald known to be in existence 
at the present time is one owned by the Duke of Devonshire. This 
is an uncut, six-sided crystal, about two inches long, and of the same 
diameter. It is of perfect color, almost flawless, and quite transparent. 

Aquamarines and other beryls are found in Siberia, India, Brazil, 
and in many localities in the United States. Pieces suitable for cutting 
are quite frequently found, and the cut stones are much lower in price 
tnan the emerald. Large stones are frequently obtained. Dana mentions 
an aquamarine from Brazil which approaches in size, and also in form, 
the head of a calf. It weighs 225 ounces troy, is transparent, and 
without a flaw. In the Field Columbian Museum is to be seen a beau- 
tiful cut aquamarine from Siberia more than two inches in diameter, 

102 



which weighs 331 carats. Here is also the finest specimen of blue 
beryl ever cut in the United States. It was found in Stoneham, Maine, 
is rich sea-green color in one direction and sea-blue in another. It 
weighs 133 carats. Numerous other Maine localities have furnished 
gem beryls. Golden beryls are found in Maine, Connecticut, North Caro- 
lina, Pennsylvania, and other United States localities, as well as in Siberia 
and Ceylon. From them are obtained gems of rich golden color resem- 
bling topaz or citrine. 

Beryl of a pale rose color is sometimes found, and when of good 
quality is cut for gem purposes, but it is of too rare occurrence to be 
important. A variety of beryl containing two to three per cent of the 
metal caesium is found at Hebron, Maine, which affords transparent, 
colorless stones of a brilliant luster. 

Aquamarine and other varieties of beryl seem not to have been 
as highly esteemed as emerald by the ancients, although beryl is men- 
tioned in the Bible, and early writers describe gems evidently belong- 
ing to the species. A notable biblical mention is that found in the 
Song of Solomon, where it is said: 

"0 daughters of Jerusalem, 
This is my beloved and this is my friend, 
His hands are as gold rings set with the beryl." 

The beryl was believed, in the Middle Ages, to give its wearer insight, 
second sight, and foresight, to induce sleep and compose the heart and 
mind. It was called " the sweet-tempered stone." It was especially 
used in the seventeenth century for divination, the method being to 
suspend a ring containing a beryl in a bowl filled with water. The edges 
of the bowl being marked with the letters of the alphabet, the beryl gave 
answers to questions asked by stopping before certain letters. It was 
also supposed to possess special power over evil spirits, and it was said 
that a man might call a devil out of hell and receive answers to such 
questions as he might ask if he but held a beryl in his mouth. The 
globe in the English crown is surmounted by a blue beryl, in allusion 
perhaps to the supposed magical power of the stone. 



103 



EUCLASE 

Euclase is a rare mineral, resembling beryl in color and hardness, 
and like it a silicate of glucina and alumina. It differs from beryl, 
however, in containing water in its composition, in being monoclinic 
in crystallization, and in having higher specific gravity. The percen- 
tage composition of euclase is: Silica 41.3, alumina 35.2, glucina 17.3, 
and water 6.2. Its specific gravity is 3.05-3.10. It barely fuses before 
the blowpipe, and is not attacked by acids. It has a vitreous luster, 
which becomes more brilliant on polishing a surface. The cut stones 
are made from transparent crystals, which range from colorless to blue 
and green, the latter resembling Russian topaz and aquamarine. Brazil 
and the Ural Mountains furnish practically all the euclase thus far 
known, and this in but small quantity. The Brazilian euclase is found 
at Boa Vista, in the province of Minas Geraes, in the same locality 
with yellow topaz. It occurs in nests in quartz veins which penetrate 
the schists of the region. The crystals found in the Urals are larger, 
one three inches in length being known. ^Euclase is also found in the 
auriferous gravels of the Sanarka River in the Government of Orenburg, 
Russia, chrysoberyl and topaz being accompanying minerals. Euclase 
possesses a strong cleavage, which gives it its name, and makes it some- 
what difficult to cut. On account of the rarity of the mineral good 
stones command a high price. 



PHENACITE 

Phenacite affords transparent, colorless gems of a brilliant vitreous 
luster. They are usually cut as brilliants, and stand between the dia- 
mond on the one hand and rock crystal on the other in the amount of 
u fire" they display. Phenacite has stronger double refraction than 
quartz, and a higher index of refraction. It is far, however, from 
equaling the diamond in these properties. In fact, it resembles quartz 
so much that it was not until 1833 recognized as a distinct species. 
The name of phenacite, from the Greek phenax, a deceiver, was given 
to it because of this resemblance. Like beryl and euclase, pheuacite 
is a silicate of glucinum. Its percentage composition is, silica 54.45, 
glucina 45.55. It is infusible before the blowpipe, and can be distin- 
guished chemically from quartz by putting a drop of cobalt nitrate on a 
heated fragment and then reheating. The fragment turns blue if phena- 
cite ; if quartz it remains black. Phenacite is harder and slightly heavier 
than quartz, its hardness being 7.5-8, and its specific gravity 2.97-3. It 
crystallizes in the rhombohedral division of the hexagonal system. The 
gems are usually obtained from crystals. 

Phenacite is not a common mineral, and nearly all that has been cut 
for gems has come from two localities, '^Takovaya, near Ekaterinburg, 
Russia, and Mt. Antero, Chaffee County, Colorado. The first locality 
furnishes the finest and largest stones, some of them weighing thirty to 
forty carats. They occur together with emerald and chrysoberyl in 
mica schist. The Mt. Antero phenacite is found at an elevation of 14,000 
feet, and is obtainable for only a short period during the summer on 
account of the abundant snows of the region. This locality affords 
smaller gems than the Russian, and owing to the demand for them as 
mineralogical specimens, few are cut. They usually occur implanted 
on quartz, beryl, or feldspar. Some good phenacite has been found 
on Bald Mountain, near North Chatham, New Hampshire, in a granite 
vein and near Florissant, Colorado. Besides being colorless, phenacite 
may exhibit pale rose and wine-yellow colors. 



105 



CHRYSOBERYL 

This mineral is like beryl in containing the element glucinum 
(beryllium), but in other respects is a distinct species. Chrysoberyl has 
no silica in its composition, as has beryl, but is composed of glucina 
and alumina, the theoretical percentages being glucina 19.8, alumina 
80.2. In nature, however, some other oxides are usually present as 
impurities or replacing the alumina. Such are iron and chromium 
oxides. Chrysoberyl is remarkable for its hardness, this being 8.5, and 
thus near that of corundum. The cut stones therefore retain a polish 
well. The specific gravity of the mineral is somewhat greater than that 
of the diamond, being 3.5 to 3.8. It crystallizes in the orthorhombic 
system, and often forms twins which are so united as to make a six- 
rayed stellate crystal, or six-sided prisms. An illustration of one of these 
crystals may be seen in the colored plate. Chrysoberyl has a prismatic 
cleavage and conchoidal fracture. Its luster is vitreous, tending to oily, 
and is brilliant. The mineral is infusible, and is not attacked by acids. 
In color it usually presents some shade of green, tending at times to 
brown or yellow. The name chrysoberyl means literally golden beryl, 
and suggests a yellow stone. While this is a common color, grass-green 
and erne raid -green are frequent and characteristic. Among jewelers 
chrysoberyl, especially the Brazilian chrysoberyl, is often known as 
chrysolite, a custom which has doubtless arisen through the similarity 
in color of the two minerals. Three kinds of chrysoberyl are employed 
in jewelry, and being given different names may be considered separately. 
These are : (1) ordinary chrysoberyl, (2) cymophane, or cat's-eye, and (3) 
alexandrite. Ordinary chrysoberyl, also called Oriental chrysolite, or 
chrysolite, is greenish-yellow to smoky-brown in color, and is employed 
as a gem only when transparent. It is for the most part obtained in 
Brazil and Ceylon, in the gem gravels of both of which countries it occurs. 
The Brazilian chrysoberyls are rolled pebbles, scarcely larger than beans, 
and occur together with topaz, garnet, tourmaline, quartz, etc., in the beds 
of streams chiefly in the northern part of the province of Minas Geraes. 
The stones occur in the neighborhood of granite and gneiss, and were 
therefore probably originally formed in these rocks. The (Ceylonese 
chrysoberyls are likewise found in stream beds, and come from Sa^ra- 

106 



gam and the neighborhood of Matura in the southern part of the island. 
In North America, chrysoberyl has been found in Maine, Connecticut, and 
North Carolina, but few stones sufficiently transparent for cutting occur. 
Cymophane, or "cat's-eye," is a name given to a translucent, opalescent 
variety of chrysoberyl, across a polished surface of which may be seen 
to play a single long, narrow ray of light, changing position with every 
movement of the stone. The phenomenon is like that exhibited by star 
sapphires, except tiiat but a single ray is seen instead of several. The 
cause of the appearance is believed to be multitudes of minute tube-like 
cavities in the stone arranged in parallel position, which reflect the light 
which falls upon them. In cutting the stone the best effect is produced 
by giving it the form of a long oval, over the middle of which a light 
ray runs and produces a resemblance to the eye of a cat. Such stones 
are the true "cat's-eyes" of jewelry, the quartz cat's-eye being much 
inferior. The name cymophane, also applied to these stones, comes from 
two Greek words, meaning wavy appearance. The cat's-eye variety of 
chrysoberyl occurs together with the transparent kind above described 
in the alluvial deposits of Ceylon and Brazil. The stones are not large, 
rarely exceeding 100 carats in weight. The largest and finest known is 
in the South Kensington Museum of England, and is about an inch and 
a half in length and of the same thickness. 

In Oriental countries the cat's-eye has long been highly esteemed a 
preserver of good fortune, the belief being that each stone is inhabited 
Iby a good spirit. It is believed to be a guardian of its owner's wealth 
and to protect him from poverty. The stone is often carved by Orientals 
into the form of some animal's head, thus increasing its weird and 
mysterious aspect. The popularity of the stone among Europeans was 
suddenly increased a few years ago when the^Duke of Connaught gave 
one in a betrothal ring to his bride, Princess Margaret of Prussia. Cat's- 
eye immediately became the fashion among the wealthy classes, and the 
supply proved quite unequal to the demand. The stone is still quite 
fashionable, and not less than one hundred dollars per carat must often 
be paid to secure a good one. 

Alexandrite is a variety of chrysoberyl found in the Ural Mountains, 
and received its name from the fact that it was first found on the birth- 
day of Alexander II., Czar of Russia, in the year 1830. Moreover, the 
colors which it presents, green and red, are the national colors of Russia. 
Alexandrite by ordinary light is dark grass-green, or emerald-green, in 
color, but on holding it to the sunlight, or viewing it by artificial light, 
it appears columbine-red. The gem has therefore the unique property 
of appearing as "an emerald by day and amethyst by night." The 

107 



locality where alexandrite was originally found, and where most of it 
has been obtained, is ^akovaya, near Ekaterinburg. Only the trans- 
parent pieces can be used for gems, and as these are relatively scarce, 
the price of the gem is high. Of late alexandrite has been found in 
the gold sands of Sanurka in the southern Urals, but a more impor- 
tant source of supply has appeared in Ceylon, where gems much 
larger than those in the Urals, and in a fine variety of colors, have 
been found. 



108 



ZIRCOtf 

Zircon is a mineral remarkable among those employed as gems for its 
high specific gravity and adamantine luster. For these reasons the color- 
less, transparent stones are sometimes employed as substitutes for the dia- 
mond, although they lack the high refractive power and hence play of colors 
of the latter. The stones are sometimes called "Matura diamonds," 
because of their abundance at Matura in the island of Ceylon. The color- 
less, or smoky zircons, are often known as " jargons " or " jargoons," 
a name said to have been given in allusion to the fact that though 
they resembled the diamond in luster they had really much less 
value. Besides zircons of this sort there are those known in jewelry 
as " hyacinth " or " jacinth," which are transparent zircons of a brown- 
ish, red-orange color. A stone of a nearly similar color is furnished 
by the essonite variety of garnet, and this is also often known as 
hyacinth. 

The high specific gravity of zircon above referred to is more than 
four times the weight of water, determinations giving results varying 
between 4.2 and 4.86. Zircon is thus the heaviest of gems, and will 
sink at once in any of the ordinary heavy liquids. The hardness 
of zircon is between that of quartz and topaz, being 7. Its index 
of refraction is high, being 1.92, or near to the diamond among gems, 
a fact which accounts for its brilliancy when cut. Before the blowpipe 
zircon is infusible. It is not acted upon by acids except in fine powder 
by sulphuric acid. In composition it is a silicate of zirconium, the per- 
centages being silica 32.8, zirconia 67.2. It usually also contains a little 
iron oxide. It is not an uncommon mineral in rocks, occurring in 
crystals of microscopic size, and in crystalline rocks it sometimes 
occurs in large and abundant crystals. These are usually opaque and 
of no value for gem purposes, although they are mined to some extent at 
the present time for use in incandescent lights. Opaque zircon is found 
in this country in Georgia, Colorado, New York, and Canada. The 
form of the crystals is usually that of four-sided prisms terminated 
by pyramids. The transparent zircons available for gems, that is, the 
so-called " noble " zircons, come almost wholly from the island of Ceylon, 
where they occur in the gem gravels that contain also rubies, sapphires, 

109 







garnets, tourmalines, etc. The zircons are in the form of rolled pebbles, 
rarely of large size, few stones of over ten or twelve carats weight 
being found. In other localities some noble zircons are found in pan- 
ning for gold, the high specific gravity of the zircon causing it to stay 
in the pans almost as long as the gold. Along the Espailly River, 
in Auvergne, France, are found zircons which yield brilliant though 
small stones of the true jacinth color. Neither in the form of hyacinth, 
or jargoon, is zircon at the present time very extensively used in jewelry, 
although it has many of the qualities desirable for gems. The best 
stones are rarely valued now at more than ten dollars per carat, 
although they were once highly prized. One peculiarity of zircon 

that should be noted 
is the change of its 
color which some- 
times takes place on 
long exposure to 
light, the color 
sometimes thus dis- 
appearing altogeth- 
er. It is usually, 
also, driven out by 
heating. As it has 
been found that the mineral when heated away from oxygen does not 
lose or change its color, the conclusion is drawn by some that the 
color depends on the state of oxidation of contained iron; but others 
think it of organic origin. The red varieties of zircon are sometimes 
sold for rubies, but they may be easily distinguished from true rubies by 
their lower hardness and higher specific gravity. Zircon becomes phos- 
phorescent but not electric upon heating. 

The ancients employed a stone which they knew as hyacinth; but 
its color was bluish, and hence it is generally supposed to have been 
our sapphire or amethyst. The lyncurion of Theophrastus is more likely 
to have been our zircon, the ancients having employed it for making 
signets, some of which are still preserved. In the Middle Ages hyacinth 
was supposed to have the power of procuring sleep, riches, honor, and 
wisdom, and of driving away plagues and evil spirits. Cardanus, writing 
in the sixteenth century, says that he was accustomed to carry a hya- 
cinth (jacinth) about with him for the purpose of inducing sleep, which 
" it did seem somewhat to confer, but not much." 



Forms of zircon crystals 



110 




429 



Green Tourmaline (Brazil). 

Green Tourmaline (Haddam, Conn.) 

Cross Section of Green Tourmaline (Cal.) 



TOURMALINE. 
Red Tourmaline or Rubellite (Island of Elba). 

Brown Tourmaline (Gouverneur, K. Yj 
Red Tourmaline or RuUellite, in Lepidolite (Cal.) 



COPymiMT 1(03, IV A. W. MUMFOHO, CHNMO. 

Black Tourmaline (Finland). 



TOURMALINE 

Early in the eighteenth century some children of Holland, playing 
on a warm summer's day in a courtyard with a few bright colored 
stones, noticed that these possessed a strange power when warmed by 
the heat of the sun. They attracted and held ashes and straws. On 
reporting this strange discovery to their parents the latter, it is said, 
could give no explanation of the curious property, but left a record 
of their knowledge of it in the name of " aschentreckers," or "ash- 
drawers," which they gave the stones, and by which they were known 
for a long time. 

This was the method of introduction to the civilized world of the 
mineral now known as tourmaline, a mineral which in variety of color, 
composition, and properties is of considerable interest in Nature. 

The lapidaries who had given the Dutch children the stones for play- 
things did not recognize them as different from the other gems with which 
they were accustomed to deal. So to the present day, although tour- 
maline is considerably used in jewelry, it is rarely ever called by that 
name. The green varieties are often known as Brazilian emerald, chrys- 
olite, or peridot, some varieties of blue as Brazilian sapphire, others as 
indicolite, the colorless as achroite, and the red as rubellite, siberite, and 
even as ruby. 

It is only somewhat recently that these different stones have been 
recognized as being varieties of a single mineral species which is known 
by the name tourmaline. This name comes from a Cingalese word 
(turamali), which was applied to the first tourmaline gems sent from 
Ceylon to Holland. 

At one time the name schorl was chiefly applied to the species. This 
was before the means of distinguishing mineral species were as well 
understood as they are now, and a large number of minerals, and even 
rocks, were included under the name schorl. One by one, however, they 
were distinguished by separate names until schorl included only tourma- 
line, and shortly afterward the name schorl was dropped altogether. 

In its opaque form, colored either black or brown, tourmaline is a 
comparatively common mineral. It accompanies many so-called meta- 
morphic rocks, and is also common in granite and other eruptive rocks. 

ill 



As a rock-forming mineral it often occurs as long, slender prisms, fre- 
quently about the size of a darning-needle, and radiating in all directions. 
The only mineral for which it is likely to be mistaken in this form is 
hornblende. It can be distinguished from this in the following manner : 
On fusing the powdered mineral with a mixture of bisulphate of potash 
and fluor-spar (best done on a little loop of platinum wire) tourmaline 
will color the flame green, while hornblende will produce no coloration. 

The black opaque crystals of tourmaline often reach a large size, some 
being known four feet in length. Both black and brown tourmaline are 
usually opaque, and hence have no value as gems. Tourmaline of other 
colors, however, is often transparent, and this is of gem value. 

The gem tourmalines are to be found in only a few localities. They 
occur in Maine, Connecticut, and California in our own country, and 
also in Brazil, Russia, and Ceylon. The crystals are usually in the 
form of long, slender prisms, often having the peculiarity of being differ- 
ently colored in different portions. Thus a crystal may be green at 
one end and red at the other, and in cross-section may show a blue 
center, then a colorless zone, then one of red, and then one of green. 
Some of the crystals from Paris, Maine, change from white at one termi- 
nation to emerald green, then light green, then pink, and finally are 
colorless at the other termination. In some crystals again the red passes 
to blue, the blue to green, and the green to black. 

Exactly what produces these differences of color is not known. It is 
known that black tourmaline has an excess of iron, the red and green an 
excess of sodium and lithium, and the yellow and brown an excess of 
magnesium in their composition. These same differences of composition 
characterize similar colors in portions of the same crystal as well as 
separate crystals. Hence the evidence is quite conclusive that the color 
in some way depends on the composition. Many transparent tourma- 
lines, while appearing of a uniform color when viewed in any one 
direction, exhibit different colors when viewed in different directions. 
Thus, one of the long, slender crystals may appear green when held 
lengthwise in front of the eye, but when looked at from the end appears 
brown. Again, some crystals appear perfectly transparent when viewed 
perpendicularly to the sides of the prism, but when viewed from the end 
are nearly opaque. This may be true even when the thickness is less 
in the latter direction. Both these properties are due to the arrange- 
ment of the molecules of tourmaline, which is such as to make the power 
of absorbing light different in different directions. 

The form of crystals of tourmaline is usually that of a three-sided 
prism. The sides of the prism are usually marked by narrow parallel 

112 



lines called striae, and the prism may be more or less rounded by the 
addition of other planes. 

If a doubly terminated crystal be examined carefully, it will be 
seen that the planes on the two ends are not alike, either in number or 
inclination. On one end there may be three planes, on the other six, 
or even twelve. If the planes on one end make a blunt termination, 
those on the other may make a sharply pointed one. Such a peculiarity 
of crystal form is possessed by but few minerals. Those possessing it 
are said to be hemimorphic, i. e., half formed. Some minerals, among 
which is tourmaline, which exhibit this peculiarity of form are often 
also pyroelectric, i. e., become electric on heating. It was this devel- 
opment of electricity which caused the stones with which the Dutch 
children played, to pick up ashes, etc., when the stones were warmed 
by the heat of the sun. Any one can repeat their observation by 
gently heating crystals, or even fragments of tourmaline, and applying 
them to bits of paper. The electrical attraction will often be found to 
be very strong, though it varies with different crystals. The fragments 
should not be overheated, the electricity being most strongly developed 
between 100 and 200 Fahrenheit. 

In composition tourmaline is a complex silicate, chiefly of aluminum 
. and boron. Iron, magnesium, the alkalies, and water also enter in vary- 
ing amounts into it. In fact, so complicated is its chemical nature that 
perhaps no other mineral has been so often analyzed or had its analyses 
so much discussed. 

Ruskin, in his "Ethics of the Dust," thus describes the composition 
of tourmaline : "A little of everything; there's always flint and clay and 
magnesia in it ; and the black is iron according to its fancy; and there's 
boracic acid, if you know what that is, and if you don't, I cannot tell you 
to-day, and it doesn't signify ; and there's potash and soda ; and on the 
whole, the chemistry of it is more like a mediaeval doctor's prescription 
than the making of a respectable mineral." 

Tourmaline is both harder and heavier than quartz, its hardness 
being 7-7.5, and its specific gravity 2.98-3.20. It is thus sufficiently 
hard for use as a gem. It is, however, quite brittle, and even at times 
friable. Cracks therefore frequently cut across good crystals, and spoil 
what would otherwise make a good gem. It is very common to find 
tourmalines in the rocks broken into a number of pieces, and the frag- 
ments "mended " together with quartz or calcite. This has been true of 
the black tourmaline shown in the accompanying plate. Scarcely any other 
mineral exhibits this change so often as tourmaline, a result due probably 
to its brittleness and the character of the rock in which it occurs. 

113 



The strong dichroism of tourmaline should be borne in mind in cut- 
ting gems from it. Since a crystal looked at in the direction of the 
vertical axis is usually much less transparent and of less pleasing color 
than when seen at right angles to this direction, gems should be cut with 
the table parallel to the prism. They will then exhibit their most pleas- 
ing color in the direction in which they are usually seen. 

Of the different colors of tourmaline used for gems, red shades are 
less abundant, and more highly prized than green. Of the red tourma- 
lines, those dark red are most valued, especially if, as is sometimes the case, 
a color like that of the ruby is exhibited. A rose-red color is, however, 
more common. The green tourmalines are usually dark green, shading 
to blue or yellow, and almost never exhibit the true emerald-green. Blue 
tourmalines are least abundant of any, and are rarely cut. Their color is 
usually an indigo-blue. Tourmaline is not attacked by acids, and the 
transparent varieties are infusible. Partly on account of its lack of 
strong color, and partly because it is not better known, tourmaline has 
not hitherto obtained much popularity as a gem, although its hardness, 
dichroism, and transparency are such as to warrant its more extensive use. 

Recently, however, it has obtained more favor, and the supply of 
Brazilian tourmalines especially is hardly equal to the demand. 

One of the best known localities for gem tourmalines is Paris, Maine. 
It was discovered by two boys, by name Elijah L. Hamlin and Ezekiel 
Holmes. They were interested in the study of minerals, and spent much 
of their leisure time searching for them. One day in the fall of 1820, 
having been out many hours hunting for minerals, they were about to 
return home when a gleam of something green at the roots of a tree 
caught their eye. Eagerly bringing it to light, they found it to be a 
beautiful green tourmaline. A fall of snow that night prevented their 
obtaining more of the crystals, but the following spring they returned 
and secured many fine gems. The locality has been extensively worked 
since then, and has furnished many fine gems, which have gone to adorn 
the coronets of kings and enriched the mineral cabinets of the world. 
The tourmaline occurs in pockets in pegmatitic granite. Black tour- 
maline, muscovite, and lepidolite are of constant occurrence through the 
granite. The granite is overlaid by mica schist, which at present is 
being stripped off to permit of further mining. It is estimated that fifty 
thousand dollars' worth of tourmalines have been taken from this one 
locality. Auburn and Rumford, Maine, are two other neighboring locali- 
ties where good gems have been found. At Haddam Neck, Connecticut, 
fine transparent tourmalines occur, generally green in color, and many 
of them of gem quality. They occur in granite. 

114 




Tourmaline mine, Mt. Mica, Paris, Maine 




Tourmaline mine, Haddam, Conn. 
115 



The red tourmaline (rubellite) from California, illustrated in the 
accompanying colored plate, is found in San Diego County of that State. 
The matrix in which it occurs is a lithia-bearing mica ( lepidolite ) of a 
delicate violet color. In this matrix the tourmaline usually occurs in 
radiating masses. The rose color of the tourmaline contrasting with 
the violet of the lepidolite makes an object which is quite a favorite 
with mineral fanciers, although the former is not sufficiently transparent 
to be used as a gem. At two other localities in the same State large 
transparent tourmalines of varying colors have been found. 

Tourmaline is found frequently in Brazil in the gem gravels, accom- 
panying topaz, amethyst, diamond, etc. It is mostly green in color, 
and is known as Brazilian emerald, it having been for a time mistaken 
for emerald. 

('In the Ural Mountains, near Ekaterinburg, crystallized tourmaline 
occurs in cavities in granite, accompanying amethyst, beryl, topaz, etc. 
These crystals often have a fine dark red color, and produce the gems 
known as Siberian rubies. They are especially prized in Russia. 

\ A.lthough the name tourmaline came from Ceylon, the gem there 
known by that name is hyacinth. True tourmaline occurs, however, on 
the island in the gem gravels. This is usually of a yellowish-green color, 
and is often known as Ceylonese chrysolite. | 

On the Island of Elba are also obtained tourmalines, generally red 
in color, transparent, and well crystallized. They are, however, not 
extensively used as gems, on account of their small size. 



or THE 
UNIVERSITY 

OF 




116 



LEPIDOLITE 

This variety of mica is attractive on account of its pink or lilac 
color. It usually occurs in scaly, granular masses, which often have 
sufficient coherence to admit of carving them into various ornamental 
objects, such as paper-weights, small vases, and boxes. They are some- 
what easily scratched, since the hardness of lepidolite is only 2.5-4. Lepi- 
dolite is often known as lithia mica, on account of its content of lithium, 
four per cent to five per cent. This affords a criterion for the determi- 
nation of the mineral, as a fragment heated before the blowpipe gives 
the purple-red flame of lithia. 

/The principal European deposit of lepidolite which has been used 
for ornamental purposes, is that at Rozena, in Moravia, where a quantity 
of the mineral of an especially pleasing rose-lilac color occurs. In the 
United States, lepidolite occurs at Paris, Rumford, and several other 
points in Oxford County, Maine, and in California, eight miles from 
San Diego. The deposit at the latter place is an extensive one, and 
is mined for lithia salts. This lepidolite is penetrated by crystals of rubel- 
lite, giving an effect as shown in the colored plate. Although some of the 
American lepidolite is nearly equal to the European in quality of color, 
no use seems as yet to have been made of it for ornamental purposes. 



117 



SPODUMENE 

Spodumene is the only one of the gem minerals except tourmaline 
and lepidolite, which contains the element lithium in any large amount. 
It is a silicate of alumina and lithia, having the percentages, silica 64.5, 
alumina 27.4, and lithia 8.4. It fuses rather easily before the blowpipe, 
and gives the purple-red color of lithia to the flame, making a con- 
venient means of distinguishing the species. Its hardness is 6.5-7, and 
specific gravity 3.1-3.2. Its luster is vitreous. Ordinarily it is opaque, 
and of a white or gray color, the word spodumene being derived from 
the Greek spodios, meaning ash-colored. 

Spodumene crystallizes in the monoclinic system, often forming large 
crystals up to four feet in length. The use of spodumene as a gem 
is confined almost exclusively to a transparent emerald-green variety 
occurring in North Carolina, and a yellow variety, also transparent, 
obtained in Brazil. The emerald-green spodumene is known as hidden- 
ite, after W. E. Hidden, who first developed it. It occurs in thin, bladed 
crystals, varying from colorless through yellow to an emerald-green 
color. These afford only small gems, none over five carats being obtain- ^ 
able. A high price has been obtained for these, ranging between 
forty dollars and one hundred dollars per carat. They are cut into 
step or table stones, as this best exhibits their dichroism, and avoids 
the danger of splitting from the marked prismatic cleavage present. 
All the hiddenite thus far known has been obtained at Stony Point, 
Alexander County, North Carolina, and this locality is now exhausted. 

The yellow spodumene, above referred to as obtained in Brazil, was 
long thought to be chrysoberyl. Its distinction from chrysoberyl, by the 
properties above mentioned, is easy, although its use in jewelry is simi- 
lar. Pieces of spodumene, of a beautiful blue color, are also occasion- 
ally found near Diamantina, in Brazil. Quite recently spodumene has 
been found near Pala, San Diego County, California, in the form of large 
transparent crystals of an amethystine hue. These afford large, hand- 
some gems, resembling amethyst in color, but distinguished from it by 
their dichroism and their rose to lilac shades. The name of kunzite has 
been applied to this variety of spodumene. 

118 




453 



Topaz with Mica and Feldspar (Russia), 
'iopaz (Bi-axil). 



TOPAZ 
Topaz in Rhyolite (Utah). 



Topaz (Japan). 
Waterworn Topaz (Brazil). 



TOPAZ 

Remarkable clearness and transparency, capacity of taking a high 
polish, and hardness and weight greater than that of quartz are the 
qualities in which topaz excels as a gem. Numerous other stones 
of inferior quality masquerade under its name, however, and this fact 
may account for the decline in popularity which the stone has suffered 
in recent years. True topaz is a silicate of alumina, containing hydroxyl 
and fluorine. Its hardness is 8, and it thus scratches quartz. Topaz 
is also remarkably heavy, considering its composition, it being three 
and one-half times as heavy as water. Owing to this unusual specific 
gravity, those accustomed to handling gems can frequently pick out 
the topaz from a miscellaneous lot of precious stones without remov- 
ing their wrappings. 

/ ^The color typically associated with topaz in its use as a gem is yellow. 
Yet the mineral species exhibits many other shades of color, which, when 
present in crystals of sufficient clearness and purity, answer equally 
well for gem purposes. These other shades, most of which are repre- 
sented in the accompanying plate, are grayish, greenish, bluish, and 
reddish. Topaz may also be quite colorless. The yellow color of the 
Brazilian topaz can be changed by heating to a pale rose-pink, and 
the gem is often treated in this way. The degree of heat employed 
is not high, and both heating and cooling must be performed gradu- 
ally. The selected stone may be packed in magnesia, asbestos, or lime, 
and heated to a low, red heat, or it may be wrapped in German tinder 
and the latter set on fire. Only stones of a brown-yellow color yield 
the pink ; the pale yellow stones turn white when so treated. Once the 
pink color is obtained it is permanent. The natural colors of topaz 
are in general perfectly durable, although some of the deep wine-yellow 
topazes from Russia fade on exposure to daylight./ 

Topaz is infusible before the blowpipe. It is not affected by hydro- 
chloric acid; but is partially decomposed by sulphuric acid, and then 
yields hydrofluoric acid. If the latter experiment is tried in a closed 
glass tube, the formation of the hydrofluoric acid is made evident by 
the etching and clouding of the walls of the tube. The powdered stone 
should be mixed with acid sulphate of potash for this experiment. 

119 




\ 




Forms of topaz crystals 



Another test for topaz is to heat the powdered mineral with cobalt 
nitrate, when it assumes a fine blue color, due to the alumina 
which it contains. 

The crystals of topaz belong to the orthorhombic system of crystal- 
lization. They are usually elongated in the direction of the prism, and 
have sharp, bright faces. They vary much in size, and often are large. 
One crystal weighing twenty-five pounds was found in Siberia. Large 
gems of topaz are, therefore, quite easily obtained. Perhaps the largest 
cut topaz known was recently presented to Pope Leo on the occasion 

of his silver jubilee (1902). 
This stone weighed nearly 
four pounds. It was obtained 
originally in Brazil. 

A well-marked character- 
istic of all topaz crystals is 
their tendency to cleave 
across the prism parallel with 
its base. Such a cleavage 
plane can be seen cutting across the crystal shown in the upper right- 
hand corner of the accompanying plate. This cleavage is so marked, and 
the cleavage plane so bright and flat, that in cutting topaz for a gem 
a cleavage surface is used as the upper face of the gem, and the other 
faces formed around it. Owing to this easy cleavage the owner of a cut 
topaz should be careful not to let the stone drop, as it might be thus 
cracked or broken. Topaz takes a high polish, and colorless gems 
of the mineral resemble the diamond considerably. They are, however, 
softer, and have weak double refractive and dispersive power. 

txThe name topaz is derived from the Greek name Topazios, which 
is that of an island in the Red Sea. The gem known to the ancients 
as topaz, however, was probably not our topaz, but chrysolite. Topaz 
usually occurs in gneiss, or granite, with tourmaline, mica, beryl, etc. 
In Brazil it occurs in a talcose rock, or in mica slate. It is sometimes 
in sufficient abundance to form an essential rock constituent. When 
so occurring, however, it has not the transparent gem quality, but is 
white and opaque. Much of the Brazilian topaz occurs as rolled 
pebbles, one of which is shown in the accompanying plate. These 
occur in the beds of streams, having been left behind, owing to their 
superior hardness, after the rock in which they were formed has been 
washed away. When colorless they are known in the region as 
pingos d'agua (drops of water). The Portuguese call them " slaves' dia- 
monds." A stone in the crown of Portugal, reputed to be a diamond 

120 



of 1,680 carats weight, and called the Braganza, is probably a topaz 
of exceptional clearness and beauty. 

The Brazilian topazes come mostly from the province of Minas G-eraes. 
While those of greenish and bluish shades are found mostly in the form 
of rolled pebbles, the yellow Brazilian topaz is found in the mother 
rock. This is a decomposed itacolumite, of a white or yellow color. 
The principal locality is near Ouro Preto. 

! />The Russian topazes like that shown in the colored plate, come 
from the Imperial mines in the Urals. Alabashka, near Mursinka, 
is one of the most productive localities. The crystals occur in cavi- 
ties, in granite, and are accompanied by crystallized smoky quartz, 
feldspar, and mica. Superb gems are cut from these topazes, a fine 
series of which is possessed in this country by the Field Columbian 
Museum and the United States National Museum. The Russian mines 
are owned and operated by the Russian Government, and the finest 
specimens are reserved for the Imperial Cabinet.' ^In the southern 
Urals, in the gold washings of the River Sanarka. yellow topazes are 

found closely resembling those of Brazil. Associated with them are 
a . j 

amethysts, rubies, chrysoberyls, and many other precious stones. /^Topaz 
crystals of good size and color are found quite abundantly in Japan, 
although they have not yet been cut for gems to any extent. There 
are many localities in the United States where topaz occurs, and it 
is often of gem quality. The group shown in the plate illustrates 
the occurrence of topaz at Thomas Mountain, Utah, a locality forty 
miles north of Sevier Lake. These crystals are found in cavities in 
the rock. They are never very large, but are usually clear and bright. 
They occur in somewhat similar fashion at Nathrop, Colorado. In the 
Eastern States topaz was first found at Trumbull, Connecticut. It 
is here quite opaque, and not suitable for gem purposes. Good gem 
topaz has been found at Huntington and Middletown, Connecticut, 
however, and at North Chatham, New Hampshire. In these locali- 
ties it occurs in pegmatitic granite. 

Of other stones which are sold under the name of topaz, the most 
common is the so-called Spanish or Saxon topaz. This is simply smoky 
quartz, heated until it turns a yellow color. It can easily be distin- 
guished from true topaz by the properties of the latter above given. 

At the present time it is also quite a common practice to vend 
ordinary colorless quartz under the name of topaz. These practices 
are harmful to the reputation of true topaz, as these forms of quartz 
lack several of the desirable qualities of that stone. The so-called 
Oriental topaz is a yellow form of corundum. It is heavier and harder 

121 



than true topaz, and more valuable. fL About forty years ago topaz was 
quite popular as a gem, and commanded three or four times its present 
price. At the present time a stone weighing several carats may be 
bought for two or three dollars. ) 

Topaz is often referred to by ancient writers, and is mentioned in 
the Bible as one of the stones to be put in the ephod of the high 
priest, as one of the gems worn by the king of Tyre, and as forming 
one of the gates of the Holy City. The gem referred to in these 
instances is, however, the modern chrysolite, while where chrysolite 
is spoken of our topaz is usually meant. 

A topaz presented by Lady Hildegarde, wife of Theoderic, Count 
of Holland, to a monastery in her native town, emitted at night, 
according to legend, a light so brilliant that in the chapel where it 
was kept prayers could be read at night without the aid of a light; 
a statement which might well be true if the monks knew the pray- 
ers by heart. 

The spiritual qualities associated with topaz are fruitfulness and 
faithfulness. It is also said to confer cheerfulness upon its wearer. 
The ancients believed that it calmed the passions and prevented bad 
dreams ; that it discovered poison by becoming obscured when in con- 
tact with it; that it quenched the heat of boiling water, and that its 
powers increased and decreased with the increase and decrease of the 
moon. Also that a topaz held in the hand of a woman at child- 
birth would lessen her suffering, and that powdered and taken in wine 
it would cure asthma and insomnia. 



122 



CYANITB 

(DISTIIENE) 

The character of this mineral in its employment as a gem is indicated 
by the derivation of its name, which is from the Greek word kuanos, 
meaning blue. While cyanite at times presents other colors, such as 
gray, green, black, and white, only the transparent blue variety is used 
for gem purposes. This is often dark blue, resembling sapphire in 
color, and cut stones may thus considerably resemble the latter. Like 
sapphire, cyanite is largely composed of aluminum, but it is a silicate 
of this metal instead of an oxide. The percentage composition of 
typical cyanite is alumina 63.2, silica 36.8. Cyanite is not as hard as 
sapphire, being 5-7 in hardness. One of its peculiarities is that the 
hardness differs in two directions. If one of the broad blades of the 
mineral be scratched in one direction a hardness of 5 is observed, while 
in a direction at right angles to this the hardness will be found to be 7. 
The name of disthene, by which cyanite is sometimes known, refers to 
the above differences, it being derived from dis, twice, or of two kinds, 
and sthenos, strong. Cyanite usually shows slight differences of color in 
different directions. It has a marked cleavage, which somewhat inter- 
feres with its use as a gem, cracks being easily started in this direction. 
Its specific gravity is comparatively high, being 3.55-3.65, nearly but not 
quite equal to that of sapphire. Its crystals belong to the triclinic system. 

Its occurrence is usually in mica schists and gneisses, it being often 
accompanied by garnet and staurolite. The decay of the mother rocks 
leaves it in form of rolled pebbles, in which manner it occurs in Russia, 
India, and Brazil. Cyanite from all these localities affords good stones 
for cutting, Monte Campione, in the St. Gothard region of Switzerland, 
furnishes some of the finest crystals known. Nearly all that has been 
used for gem purposes in this country has been obtained near Bakers- 
ville, North Carolina. The comparative softness of cyanite is a bar to 
its extensive use as a gem, although in respect to color and luster it is of 
a pleasing character. 



123 



ANDALUSITE 

This mineral has the same chemical composition as cyanite, it being 
a simple aluminum silicate. It differs, however, from that mineral in 
color, specific gravity, system of crystallization and various other proper- 
ties, so that there is little danger of mistaking the two. 

Andalusite occurs generally as an opaque mineral, commonly in argil- 
laceous and mica schists. The transparent pieces cut for gems are obtained 
almost entirely from the province of Minas Geraes, Brazil, where they 
occur in the beds of streams, together with topaz. These transparent 
pebbles have a pale green color in one direction and in another are 
brownish red. This difference of color is due to the pleochroism of the 
mineral, which is strong, and the directions of which should be borne in 
mind in cutting. It is when looked at in the direction of the vertical 
axis that the reddish color of andalusite is apparent, while at right 
angles to this the green color appears. 

Andalusite crystallizes in the orthorhombic system, the crystals 
usually taking the form of nearly square prisms. It has a marked 
prismatic cleavage, which does not, however, interfere with the cutting of 
it to any extent. Its luster is vitreous. In hardness it is somewhat 
superior to quartz, the degree of hardness being 7.5. The specific gravity 
is 3.16-3.20. Like cyanite, andalusite is infusible before the blowpipe, 
and is not attacked by acids. 

In addition to the use of the transparent forms of andalusite, men- 
tion should be made of the fact that sections of the opaque crystals are 

sometimes worn, being 
prized on account of the 
cross-like markings 
which they contain. 
These result from the 

Sections of andalusite crystal showing cross-like markings shape taken by inclu- 

sions of carbonaceous 

matter hi the crystal, which usually extend from end to end of 
the same. Peasants of Brittany prize these especially as charms, 
believing them of miraculous origin. This variety of andalusite is -tech- 
nically known as chiastolite, from the Greek chiastos, meaning arranged 

124 



diagonally, and also as made, in allusion to the use of the "mascle" in 
heraldry, which signifies a rhomb with open center. The name andalu- 
site is from the province of Andalusia in Spain, whence the mineral was 
first described. Chiastolites are found at various points in New England 
and in California in this country, but sale for them is to be found chiefly 
abroad. Kunz describes andalusite of a pink color, capable of affording 
transparent gems, which is obtainable at Westford, Massachusetts, and 
Standish, Maine. 



125 





STAUROLITE 

This mineral when sufficiently transparent to make a gem, furnishes 
a dark, brownish red stone, not unlike some varieties of garnet in color. 
It is similar also to garnet in hardness, 7-7.5, and specific gravity, 
this being about 3.7. It differs, however, in crystallizing in the 
orthorhombic system, and hence it is doubly refracting. The crystals 
usually have the shape of six-sided prisms, often grouped in the shape of a 
cross, the latter habit giving the mineral its name, from the Greek, stauros, 

a cross. Groups of this shape are found 
abundantly in Fannin County, Georgia, and 
are there known as fairy stones, under the 
belief that fairies make them. The peasants 
of Brittany wear similar crystals as charms, 
believing them of miraculous origin. The 
Penitentes of New Mexico are said also to 

have great reverence for the stone, each member of the sect being 
accustomed to wear one around his neck. A traveler endeavoring 
to buy one found it impossible to do so, the owner saying that he would 
sooner part with one of his children. The stone had been blessed by 
the priest, and its possessor believed that it insured him a long and 
happy life, and protected him from all ailments and accidents. 

In composition staurolite is a hydrous silicate of iron, magnesium, 
and aluminum. It is generally infusible, and but slightly attacked by 
acids. Rolled pebbles of staurolite occur in the gem gravels of Brazil, 
and crystals suitable for cutting into transparent stones come from Swit- 
zerland and Moravia. Staurolite is a common mineral in mica schists, 
and in such a matrix occurs in several localities in this country, but no 
transparent crystals have been found here. 



126 




or 




559 



Almandine Garnet (Alaska). 

Essonite Garnet, cut. 
Dem an told Garnet, cut. 
Demantoid Garnet (Ural Mts.). 



Alniandite Garnet, cut. 



"Cape Ruby," cut. 



Essonite Garnet and Diopside (Italy). 
Chrysolite crystal. 



Epidote (Knappenwand, Austria). 

Epidote, cut. 
.Chrysolite, cut. 
Pyrope Garnet (Bohemia). 



GARNET 

This mineral exhibits many varieties of color and of composition. 
The color probably most often thought of in connection with it is dark 
red, but it would be a mistake to suppose this the only color which it 
may manifest. Green, red, rose, and brown are other colors which garnet 
transparent enough to be used as gems exhibits, while among opaque 
garnets may be found black and many varieties of the shades above 
mentioned. 

These variations of color are more or less connected with differences 
of composition which it may be well first of all to consider. Garnet as 
a mineral is a silicate. United with silica the element most commonly 
occurring is aluminum. If calcium be united with these two, the variety 
of garnet known as grossularite, or essonite, or cinnamon stone, is pro- 
duced. If magnesium takes the place of calcium, then pyrope is formed. 
If iron, we have almandite, and if manganese, spessartite. Another 
variety of garnet, andradite, is composed of calcium and iron in com- 
bination with silica, and still another, uvarovite, of calcium, chromium, 
and silica. Though they seem to differ so much in composition, all kinds 
of garnet crystallize in the same system, and are closely allied in all 
their properties, so that it is an easy matter to distinguish garnet 
of any variety from other minerals. 




Forms of garnet crystals 

Garnet crystals may be of the twelve-sided form known as dodeca- 
hedrons, the faces of which have the shape of rhombs ; or the twenty-four- 
sided form, known as trapezohedrons, the faces of which have the shape 
of trapeziums. Quite as commonly occur crystals which are combina- 
tions of these two forms, and then exhibit thirty-six faces, as in the crystal 

127 



from Alaska shown in the accompanying colored plate. Sometimes the 
crystals attain considerable size. Perfect ones from Colorado weighing 
fifteen pounds are known, and some two feet in diameter are reported 
from North Carolina. A curious feature of garnet crystals is that of often 
inclosing other minerals. The garnets from New Mexico, for instance, 
when broken open are sometimes found to contain a small grain of 
quartz. In the crystals from East Woodstock, Maine, only the outside 
shell is garnet, and the interior is calcite. Other crystals are made up 
of layers of garnet and some other mineral. 

Garnet has a strong tendency to crystallize, and hence is usually 
found as crystals. The grains of garnet found in the sands of river beds 
and on beaches, though not often showing crystal form, may be really 
fragments of crystals. Garnet is one of the most common constituents 
of such sands because of its hardness and power of resisting decay. These 
properties enable it to endure after the other ingredients of the rocks of 
which it formed a part have been worn away. It is quite heavy as com- 
pared with the quartz, of which the sand is mostly composed, and hence 
continually accumulates on a beach, while the quartz is in part blown 
away. In such localities it will always be found near the water line, 
because the waves, on account of its weight, can carry it but a slight 
distance inland. Practically all garnet is three and one-half times as 
heavy as water, and some four times as heavy. As a rule, it is 
somewhat harder than quartz, its hardness being 1\ in the scale of which 
quartz is 7. Some varieties are, however, somewhat softer. Most varie- 
ties of garnet fuse quite readily before the blowpipe, and the globules 
thus formed will be magnetic if the garnet contains much iron. The 
green garnet, uvarovite, is almost infusible, however. Garnet is not 
much affected by ordinary acids, although it may be somewhat decom- 
posed by long heating. 

The name garnet is said by some authorities to come from the Latin 
word granatus, meaning like a grain, and to have arisen in allusion to 
the resemblance of its crystals in color and size to the seeds of the 
pomegranate. The German word for garnet, granat, is the same as the 
Latin word. Others think the word derived from the Latin name of the 
cochineal insect, in allusion to a similarity in color. 

The use of garnet for gem purposes seems to date back to the earliest 
times. Among the ornaments adorning the oldest Egyptian mummies 
there are frequently found necklaces containing garnet. The Romans 
prized the stone highly, and it is a gem much used at the present 
day, its hardness and durability and richness and permanency of color 
giving it qualities desirable for a precious stone. 

128 



Two varieties of garnet, almandite and pyrope, may exhibit the dark 
blood-red color especially ascribed to garnet. Almandite or almandine 
garnet derives its name from Alabanda, a city of Asia Minor, in the 
ancient district of Caria, whence garnet was first brought to the Romans. 
* The finest almandite for a long time came from near the city of Sirian, 
in the old province of Pegu, Lower Burmah. While this was the center 
of supply, it is not known just where the garnets were obtained. Such 
garnets are still known as "Sirian" garnets. Their color tends toward 
the violet of the ruby, and gives them a high value, j^liere are several 
localities in northern India where almandite is mined on a large scale, 
and the stone is much used in Indian jewelry. Some of these localities 
are Condapilly, Sarwar, and Cacoria/ Almandite is also found in Brazil, 
in Australia, in several localities in the Alps, and in the United States. 
Stones from all these regions are found suitable for cutting, the only 
qualifications needed being sufficient size and transparency and good 
color. The almandite of Alaska shown in the accompanying plate occurs 
in great quantities near the mouth of the Stickeen River, but has not 
been extensively cut on account of its being too opaque. Almandite 
usually occurs in metamorphic rocks, such as gneisses or mica schists; 
also in granite. It is also found in many gem gravels. From the ruby 
it can be distinguished, as can all varieties of garnet, by its lower hard- 
ness and single refraction of light. In artificial light, too, it borrows 
a yellow tint, rendering it less pleasing, while the color of ruby grows 
more intense. When almandite tends toward a brownish-red color it 
is known as vermeille. 

Pyrope, the magnesian variety of garnet, does not differ much in 
color from almandite. Both are dark red, but while almandite tends 
toward a violet tone, pyrope shades toward yellow. Pyrope is lighter 
than almandite, the specific gravity being 3.7 to 3.8, while that of 
almandite is 4.1 to 4.3. It is also less easily fusible. It rarely occurs 
in crystals, and where found in place is always associated with the mag- 
nesium-bearing rocks, peridotite or serpentine. It is thus probably always 
of eruptive origin. Pyrope is a characteristic constituent of the diamond- 
bearing rock of South Africa, and is the stone known in trade as u Cape 
ruby." These garnets afford excellent gems.l^The home of the pyrope, 
however, is, and has been for many centuries, Bohemia. Here it is found 
in many localities, but chiefly in the northwestern part, near Teplitz and 
Bilin. The garnets are found in a gravel or conglomerate of Creta- 
ceous age, resulting from the decomposition of a serpentine. Sometimes, 
however, they are found in the matrix, and are then often associated 
with a brown opal. They are found by digging and separated by wash- 

129 



Mfag. Though of good quality the stones are small, those as large as a 
hazelnut being found but rarely. Although the Bohemian garnets have 
been known for many centuries, the industry of mining and cutting them 
on a large scale is said not to have assumed any special proportions until 
the advent of foreigners to Karlsbad. They spread a knowledge of the 
stones to other countries, and a demand sprang up which has led 
to the establishment of a great industry, and made Bohemia the garnet 
center of the world. There are over three thousand men employed at 
the present time simply in cutting the stones, and if to these be added 
the number of miners and gold and silver smiths occupied in the mining 
and mounting of the garnets, it is estimated that a total of ten thousand 
persons is engaged in the Bohemian garnet industry. The stones are 
used not alone for jewelry and for ornamenting gold and silver plate, but 
also extensively for watch jewels and for polishing, f Excellent pyropes 
are found in Arizona, New Mexico, and southern Colorado in our own 
country. They occur in the beds of streams as rolled pebbles, and often 
associated with the green chrysolite or peridot of the eruptive rock from 
which they came. They are especially abundant about anthills, being 
removed by the ants because their size stands in the way of the excava- 
tions of the busy insects. The name pyrope comes from the Greek word 
for fire, and is applied on account of the color of the stone. 

Of quite similar origin is the name carbuncle, a term applied to 
nearly all fiery red stones in Roman times, but now used to designate 
garnets cut in the oval form known as cabochon. The word carbuncle 
comes from the Latin word carbo, coal, and refers to the internal fire-like 
color and reflection of garnets. 

The calcium-aluminum variety of garnet, called grossularite, cinna- 
mon stone, or essonite, is less used in jewelry than those above mentioned. 
It is usually yellow to brown in color, but may be rose-red or pink. The 
yellow grossularites resemble in color the hyacinth, and are sometimes 
sold in place of the latter, but true hyacinth is much heavier and 
doubly refracting.^ kAbout the only essonites or cinnamon stones avail- 
able for gems come from Ceylon. These are of good size and color. \ 
Those from Italy, shown in the accompanying plate, are too small 
to cut into gems, but surrounded as they are by light green chlorite 
and pyroxene, make very pretty mineral specimens. Grossularite is 
almost always found in crystalline limestone. 

Green garnets are of two kinds, the calcium-iron garnet, known as 
demantoid, and the calcium-chromium garnet, known as uvarovite. The 
demantoid garnets come only from the Urals. They have a rich green 
color, and make beautiful gems when clear and flawless. The name 

130 



demantoid refers to the diamond-like luster which they possess. The 
stone is also known as " Uralian emerald." Uvarovite, named for Count 
Uvarov of Russia, also makes valuable gems if found in pieces of suffi- 
cient size and luster. It is found in Russia, in Pennsylvania, and in 
Canada. 

That garnet has been known and used from the earliest times 
has already been remarked. Under the name of carbuncle mention is 
made of it in the literature of all ages, the feature noted being usually 
the brilliant, fiery light which it gives iorth. According to the Talmud, 
the only light which Noah had in the ark was afforded by a carbuncle, 
and there are many Oriental tales regarding the size and brilliancy of 
carbuncles owned by the potentates of the East. Occasionally carbuncles 
were engraved, and some fine garnet intaglios are still known. The 
greater abundance of the stone in modern times has led to its being less 
highly prized than formerly, and to its being put to other uses than mere 
adornment, but it perhaps contributes more largely to the comfort and 
happiness of the world as it is now used than could ever have been the 
case when it was the property only of kings. The virtues ascribed to 
the garnet in earlier times were similar to those of the ruby, but in less 
degree. It was emblematic of constancy, gave and preserved health, and 
reconciled differences between friends. It kept off plague and thunder 
if suspended from the neck, and increased riches and honors. 



131 



CHRYSOLITE 

This mineral is known among the gems by many names. It is 
often called chrysoberyl by jewelers, while the true chrysoberyl is called 
chrysolite. It is also known by different names, according to its color, 
it being called peridot when of a deep olive-green, olivine when of a yel- 
lowish-green, and chrysolite when of a lighter or golden-yellow color. 
The name chrysolite means gold stone. Again, some so-called emer- 
alds are really chrysolite, a notable case being those shown in connec- 
tion with the Three Magi in the Cathedral at Cologne. The so-called 
"Oriental chrysolite" is yellowish-green sapphire; "Ceylonese chrys- 
olite" is olive-green tourmaline ; " Saxon chrysolite " is greenish-yellow 
topaz; " false chrysolite " is moldavite; " Cape chrysolite " is prehnite, 
and so on. The various designations have evidently arisen by con- 
founding different minerals similar in color, but it is an easy matter 
in any case to distinguish the minerals by a test of their physical and 
chemical properties. One feature distinguishing chrysolite from most 
other gems is its relatively low hardness, which is 6f . It will thus 
scratch feldspar, but is scratched by quartz and most other gems. Again, 
it is relatively heavy, its specific gravity being between 3.3 and 3.4. Its 
luster, too, while vitreous, has a slightly oily character, which can be 
detected by a little experience. Chrysolite is easily dissolved by the 
common acids, especially if powdered and warmed, the silica separating 
in a gelatinous form, which is quite characteristic. In composition it is 
a silicate of magnesium and iron, the relative percentages of the two 
latter elements varying. In gem chrysolite the percentage of iron is 
usually low, and a typical composition would be: silica, 41%, magnesia, 
49.2 % , and iron protoxide, 9.8 % . Before the blowpipe chrysolite whitens, 
but is generally infusible. It crystallizes in the orthorhombic system, 
and is hence doubly refracting. The crystals have good cleavage in 
one direction and partial cleavage in another. The fracture is con- 
choidal. Chrysolite is a common constituent of eruptive rocks, but in 
grains too small and too opaque to be used for gems. 

Whence the large, transparent pieces of chrysolite used for gems 
are obtained does not seem to be known. They are reported to come 
from the Levant, from Burmah, from Ceylon, from Egypt, and from 

132 



Brazil; but the exact locality in none of these countries has yet been 
ascertained by writers. Kunz states that all the chrysolite sold in 
modern times is taken out of old jewelry, often two centuries old, so 
that it is likely that the old localities are either forgotten or ex- 
hausted. Recently, however, quite an amount of good chrysolite has 
. come from a locality in Upper Egypt, near the Red Sea, and this is 
doubtless one of the old sources of supply. The chrysolites at present 
available are not of very large size, rarely exceeding an inch in diam- 
eter. They are, however, of fine color and transparency, and make 
a desirable gem when not exposed to hard usage. For ring stones 
they scratch and wear away too easily. Excellent small chrysolites 
come from Arizona and New Mexico, being found in sand in connec- 
tion with the pyrope garnets previously mentioned. The chrysolite 
is locally called "Job's tears," on account of its pitted appearance. 
Chrysolite is an essential constituent of meteorites, and the grains 
sometimes occur in these bodies of sufficient size and transparency 
to be cut into gems of about a carat each. Such stones have a peculiar 
interest on account of their origin. 

Chrysolite is frequently mentioned in the Bible and in ancient litera- 
ture; but it is pretty certain that much of the chrysolite so named 
was our topaz. If this is true, the chrysolite of the ancients was 
found on the island of Topazios, in the Red Sea. Diodones Siculus 
says of the stone there that it was not discernible by day, but was 
bright at night, so that it could be seen by patrols. They would 
cover the luminous spot with a vase, and the next day come and cut 
out the rock at the place indicated, when, upon polishing, the gem 
would appear. The name chrysolite was also applied in former times 
to a number of other yellow gems, such as zircon and beryl, stones 
of a similar color being then usually classed together. Powdered chryso- 
lite was used as a remedy for asthma, and held under the tongue was 
believed to lessen thirst in fever. 



133 



EPIDOTE 

This is a mineral possessing several interesting characters, and hav- 
ing many qualities desired in gems, yet its use in jewelry is very 
limited. It is comparatively common as one of the constituent min- 
erals of metamorphic rocks, but in its ordinary occurrences it is not 
suitable for gem purposes. It is only when occurring in large, trans- 
parent crystals that pieces suitable for cutting can be obtained. Its 
peculiar green color is one of its most striking characters, enabling it 
nearly always to be recognized. This color is a yellowish green, known 
as pistachio - green, and is hardly possessed by another mineral. It 
frequently, however, shades to black on the one hand and brown on 
the other, so that it cannot be taken alone as a criterion for determi- 
nation. Epidote is quite strongly pleochroic ; that is, it exhibits differ- 
ent colors in different directions, being often green in one direction, 
brown in another, and yellow in another. It is usually cut so as 
to show the green color, and the stone must generally be made quite 
thin to get the proper transparency. Epidote is a rather hard and 
heavy mineral, its hardness being nearly equal to that of quartz, and 
its specific gravity 3.2 to 3.5. It is brittle, and has a basal cleavage. 
Its luster is vitreous to resinous. 

In composition it is a hydrous silicate of calcium, aluminum, and 
iron, the darkness of its color increasing with a larger proportion 
of iron. It is fusible before the blowpipe, but unattacked by acids 
before fusing, flfthe finest crystals of epidote for cutting come from 
the Knappenwand, in the valley of the Pinzgau, Austrian Tyrol. 
Specimens of these are shown in the accompanying colored plate. 
This occurrence was discovered in 1866. | Quite recently an occurrence 
of epidote, more beautifully crystallized even than that of the Knap- 
penwand, was discovered on Prince of Wales Island, Alaska ; but unfor- 
tunately these specimens are too opaque for cutting. Being a rather 
heavy mineral, epidote lingers among the pebbles of stream beds, and 
material suitable for cutting is hence sometimes found in this way. 
Brazil and North Carolina are localities where epidote of this sort 
has been found. 

134 



VESUVIANITE 

(IDOCRASE) 

This mineral affords transparent stones of pale brown, green, or yel- 
low colors, which closely resemble in appearance cut gems of smoky 
quartz, tourmaline, chrysolite, hyacinth, or essonite. They have a rich 
luster due to a combination of resinous and vitreous characters, and 
are sufficiently dichroic to be of interest from that point of view. 
Nearly all the cut stones come from the occurrence at Mount Vesuvius 
(whence the mineral obtains its name), or from one on the Mussa Alp, 
in the Ala valley of the Piedmont plateau, Italy. The crystals from 
Vesuvius are generally brownish to colorless, while those of the Pied- 
mont are green. 

The hardness of vesuvianite is 6.5, sufficient to give it a fair wear- 
ing quality. Its specific gravity is 3.35 to 3.45. In composition it 
is a complex silicate, chiefly of aluminum and calcium. It is fusible 
before the blowpipe. It has a strong tendency to crystallize, the crystals 
belonging to the tetragonal system, and usually appearing essentially 
as short, stout prisms. 

It is not an uncommon mineral, but is usually too opaque to make 
desirable gems. Its occurrence is especially associated with limestone, 
either as the result of metamorphism or direct volcanic eruption, as at 
Vesuvius. A yellowish brown variety, known as xanthite, occurs at 
Amity, New York, and an occurrence on the Vilui River, near Lake 
Baikal, Siberia, is known as viluite. 

The cut stones are made exclusively from clear crystals, which rarely 
afford stones exceeding a few carats in size. The step or table cut is 
the form usually given the stones. 



135 



IOLITE 

(DICHROITE, CORDIERITE) 

Of the different names by which this mineral is known, cordierite 
is in honor of the French geologist Cordier while the two others 
indicate important characters of the mineral first, that it is of a violet 
color (Greek, ion, violet, and lithos, stone); and second, that it has 
two colors (Greek, dichroos, two-colored). 

When cut as a gem the stone is usually known as water sapphire, 
or saphir deau. In color it resembles the sapphire closely, although 
the shade of blue which it exhibits is that known as Berlin -blue, 
instead of the cornflower-blue of the sapphire. The sapphire, however, 
exhibits nearly the same color throughout, while a cut stone of iolite, 
if blue in one direction, will be seen on turning to be gray in another. 
On this account, and by reason of its inferior hardness, it is not prized 
as highly as the sapphire, and it has but a limited use. The hardness of 
iolite is somewhat higher than that of quartz, being from 7-7.5. Its 
specific gravity is nearly similar to that of the latter mineral, being 2.6 
to 2.66. In composition it is a hydrous silicate of alumina, magnesia, and 
iron. It is barely fusible before the blowpipe, and is not attacked by 
acids. Its luster is vitreous, and its color may be imitated in glass; 
but the strong dichroism of the native mineral cannot be copied. It 
crystallizes in the orthorhombic system ; but clear, transparent crystals 
are rare, the strong tendency of the mineral to alter on exposure caus- 
ing them to become clouded and opaque. Pieces available for cutting 
occur generally as grains in granite, or gneiss, or as rolled pebbles in 
the beds of streams. /The finest of the latter come from Ceylon, and 
this is the source of most of the iolite used in jewelry/ It occurs 
similarly in Brazil, associated with topaz in stream gravels. Good iolite 
for cutting has been obtained from granite in Haddam and Guilford, 
Connecticut, in this country. Besides blue, iolite may also present 
colors of yellow, green, or brown. Only the blue is cut, however, 
and the cutting is made so as to show this color at the surface. It 
is usually given the table, or step cut, but sometimes the cabochon, 
especially if, as is sometimes the case, a star-like effect, like that of 
the star sapphire, can be obtained. 

136 



RUTILE 

This mineral has luster, hardness, and power of resistance to solvents 
sufficient to fit it for use as a gem, but ordinarily lacks transparency 
and brilliancy of color. Rutile is oxide of titanium, containing more 
or less iron. Its usual color is reddish-brown, passing into black with 
a higher content of iron. The latter variety, known as nigrine, gives, 
when cut, a stone closely resembling the black diamond in appearance. 
The luster of rutile is adamantine, like that of the diamond ; but owing 
to its being rather opaque, its luster usually borders on the metallic 
also. It is rarely sufficiently transparent to make clear 
stones of any considerable size. At times, however, pieces 
are found which cut into gems almost like the ruby. 
Rutile is the mineral which usually forms the hair-like 
crystals penetrating quartz and other minerals, and these 
often have a blood-red color. The hardness of rutile 
is 6-6.5. Its specific gravity is high, often enabling one 
to recognize it by simply taking it in the hand. It equals 
4.2. Rutile is infusible before the blowpipe, and is unattacked by acids. 

What are perhaps the finest rutile crystals known in the world 
come from Graves Mountain, Georgia. Here long, splendent crystals 
are obtained, which are objects of sufficient beauty to be worn uncut. 
It is characteristic of rutile to form groups of crystals, each meeting 
the other at an angle, so as to form a complete polygon. These objects 
make natural ornaments also. 

Rutile crystallizes in the tetragonal system. The cut stones are 
usually given the form of brilliants. 



137 



TITANITE 

(SPHENE) 

Titanite is one of the few minerals which possess, like diamond, an 
adamantine luster. This luster gives to gems cut from titanite a rich 
effect, but they lack depth of color and hardness sufficient to make them 
stones of the first rank. 

Titanite occurs in numerous colors, brown, yellow, and green being 
the most common and characteristic. Stones cut from these are usually 
distinctly -pleochroic, showing red and yellow in different directions, 
while in one direction they may be colorless. Only 
the transparent pieces are cut for gems. They 
resemble chrysoberyl, topaz, garnet, or chrysolite, in 
appearance. Their hardness is 5 to 5^, somewhat 
below that essential for a good wearing gem. The 
S hene specific gravity of titanite is 3.4 to 3.55. In compo- 

sition it is a titano-silicate of calcium, the percent- 
ages being, silica 30.6, titanium dioxide 40.8, lime 28.6. It is 
fusible before the blowpipe to a colored glass. It is attacked by sul- 
phuric and hydrofluoric acid. It crystallizes in the monoclinic system, 
the crystals often having the shape of a wedge, whence the name sphene, 
from the Greek sphen, a wedge, by which the mineral is often known. 

The finest transparent crystals of titanite come from Switzerland, 
being generally of a yellowish-green color. Kunz mentions crystals of 
titanite from Bridgewater, Bucks County, Pennsylvania, over an inch in 
length, which afford fine greenish-yellow or golden stones, weighing 10 
to 20 carats. 




138 



AXINITE 

This is a mineral occasionally cut for gem purposes, but not exten- 
sively in vogue. It furnishes a stone of a clove-brown color, transparent, 
and with glossy luster. It is somewhat deficient in hardness, being softer 
than quartz, though harder than feldspar. Hardness 6.5-7. Before the 
blowpipe axinite fuses readily, giving a pale green flame. It is not 
attacked by acids. In composition it is a boro-silicate 
of aluminum and calcium, with varying amounts of iron 
and manganese. Besides occurring of brown color, it 
may also be of blue, gray, or yellow shades, although 
brown is the most common. Like epidote, iolite, tour- 
maline, etc., axinite is strongly pleochroic, showing olive- 
green, cinnamon-brown, and violet-blue in different direc- Axinite 
tions, especially if examined with the dichroscope. It 
crystallizes in the triclinic system, usually in thin, broad blades, which so 
much resemble an ax that they have given the name of axinite to the 
mineral. 

^/The best known occurrence of axinite, and that which yields the 
finest crystals, is near Bourg d'Oisans, Dauphine, France. It occurs here 
with albite, prehnite, and quartz. / There are several other occurrences 
of the mineral in Europe and the United States, but few yield material 
of sufficient size and transparency for cutting. 




139 




The species above named form a group of black, heavy minerals, 
with pitchy or sub-metallic luster, which are occasionally cut when a- 
brilliant black gem is desired. They are peculiar in their composition 
in that they are salts of the rare earths, yttrium, cerium, tungsten 
niobium, etc. They are therefore often known as rare earth minerals. 
They have a hardness of 5-6, and a specific gravity of 5-6. The latter 
is sufficient to distinguish them from any other of the black minerals 
used in jewelry, such as jet and obsidian, the difference being at once 
noticeable on taking one of either in the hand. Their color being a rich 
velvet black, and their luster brilliant, they are superior in appearance 
to the more extensively used black minerals, and should have a wider 
vogue. Samarskite is perhaps the richest in color and luster of any of 
the series, this being a deep velvety black. The minerals are found in 
this country chiefly in North Carolina, although allanite is obtained also 
in Virginia and Texas. In Europe they are found in Norway and the 
Ural Mountains. 



140 








Rutilated Quartz, polished (Brazil). 
Rose Quartz, polished (Black Hills). 



461 



QUARTZ (crystalline). 
Smoky Quartz (Switzerland). 



IOS, ir . w. MUKFtmO, CH 



Amethyst (Virginia). 
Amethyst (Montana). 



QUARTZ 

This is the most abundant of common minerals, and one which appears 
in a great variety of colors and structures looking very unlike. In color, 
hardness, transparency, and luster many of these varieties of quartz are 
well suited for use as gems, but owing to their common occurrence they 
are less highly valued than other minerals possessing perhaps no more 
desirable qualities. Nevertheless the varieties of quartz have an extensive 
use in jewelry, and deserve description in detail. The chemical composi- 
tion of all varieties of quartz is the same, viz., oxide of silicon. The 
physical characters are likewise nearly constant, and are as follows : hard- 
ness, 7; specific gravity, 2.65; cleavage, none; fracture, conchoidal; 
infusible before the blowpipe; insoluble in common acids. 

The varieties of quartz fall naturally into two groups, the pheno- 
crystalline (plainly crystalline), and cryptocrystalline (obscurely crystal- 
line). Of these the phenocrystalline varieties will be considered first. 
These include rock crystal, amethyst, smoky quartz, rose quartz, and 
sagenitic quartz, with others of minor importance. The differences 
between these varieties are almost wholly differences of color. 

Rock Crystal. This is quartz in its purest form. Typically it is trans- 
parent and colorless, but clouded and opaque occurrences are included 
under this head. By the ancients it was supposed to be petrified ice, and 
hence the Greeks applied it to their word for ice, from which we get our 
word crystal. One reason for this belief was the fact that much of the 
quartz known to them came from the high peaks of the Alps. They con- 
cluded therefore that it was ice frozen so hard it could not melt. This 
belief must have survived nearly to modern times, for in 1676 Robert 
Boyle, the eminent physicist, thought it necessary to bring forward several 
arguments to prove the falsity of the idea. One of these arguments was 
that quartz was two and a half times as heavy as water, and another 
that it was found in tropical countries. 

Quartz in the form of rock crystal is now known to occur in all parts 
of the globe, although the occurrences of clear, transparent rock crystal 
suitable for cutting are comparatively few in number. Rock crystal is 
frequently, though not always, found in the form of terminated crystals, 
having usually the shape of six-sided prisms capped at one or both ends 

141 



by pyramids. For use in jewelry or for purposes of ornament rock 
crystal is cut, the form of cutting depending on the size of pieces that 
can be obtained clear. L The favorite use for the largest pieces is to cut 
them into spheres or balls. This was done even in the times of the 
Romans, the aristocratic ladies of that day carrying the spheres in 
summer for the sake of the coolness they afforded. The same custom 
prevails among the Japanese at the present time, and the industry of 
making the balls is extensively carried on in Japan. Balls from four to 
six inches in diameter have a high value, both on account of the rarity of 
finding so large, transparent and flawless pieces of quartz and because 
of the labor of making them// The smaller balls are somewhat in fashion 







Forms of quartz crystals 

in Europe and America at the present time as fortune tellers, the images 
of objects seen through the spheres being supposed, according to a fancy 
which has survived from an early period, to indicate the observer's future. 

A superb example of carving in rock crystal is to be seen in the 
Morgan collection of gems in the American Museum of Natural History 
of New York City. This object is a globe four inches in diameter, on 
which are outlined the continents and oceans, while a figure of Atlas 
beneath supports the sphere. 

Rock crystal is also cut into seals, paper-weights, and other orna- 
mental objects, and the small pieces are used in enormous quantities for 
cutting into stones for rings, pins, brooches, etc. These are often known 
as " rhinestones," but also as "Lake George diamonds," "Brazilian 
diamonds," and "diamonds" from whatever locality they come. These 
make desirable stones as far as durablity is concerned, and are fairly 
brilliant, but are not to be compared with the diamond in high 
refractive powers. An attempt to pass off a rhinestone for a dia- 
mond can be easily detected by the relative softness of the former, it 
being possible to scratch it not only with diamond but also with corun- 
dum or topaz. Rhinestones have little intrinsic value owing to the 
common occurrence of the raw material. They do not therefore legiti- 

142 



mately bring a price much beyond that of the labor of cutting, which is 
at present from a dollar and a half to two dollars a dozen for stones of 
the ordinary sizes. Considerable rock crystal is used for making the 
so-called "pebble" eye-glasses and spectacles. It is a common notion 
that these are more beneficial to the eyes than glass. There seems to be 
no good reason for this opinion, however, and unless the crystal is cut in 
a certain definite crystallographic direction, that is, at right angles to the 
prism, the light coming through to the eye of the wearer will be broken 
up by double refraction, and may be positively harmful in its effects. 

Another occasional use to which rock crystal is put is for making 
mirrors, for which purpose it is said to be superior to glass in that it 
does not detract from the rosiness of the complexion. 

The chief source of the rock crystal used in the arts at the present 
time is Brazil. In several provinces of that country, but especially those 
of Minas Geraes and Goyaz, large, clear masses, often in the form of 
crystals, are found loose in the soil. These are picked up and shipped to 
various markets, furnishing a supply of excellent material at small cost. 
In India considerable rock crystal is obtained from localities in the 
government of Madras, and fashioned by the natives into various 
objects. 

The French and Swiss Alps, which probably furnished the raw mate- 
rial to the Romans, still afford a small supply, of which limited use is 
made. Quartz pebbles, derived doubtless from these Alpine sources, are 
found in the bed of the Rhine and its tributaries, and it was to these when 
cut that the name of rhinestones was originally applied. 

The Island of Madagascar has since the middle of the seventeenth 
century been noted for the large masses of clear quartz to be obtained 
there. The quartz is found mostly in stream beds in the form of rolled 
masses, but also occurs in crystals. Single pieces are found weighing 
several hundred pounds. The Madagascar quartz furnishes the material 
for most of the crystal balls sold as Japanese, many of these being not 
even cut in Japan. In our own country several localities afford clear 
quartz crystals, the best known being Hot Springs, Arkansas, and Little 
Falls, New York. Those from the latter locality are doubly terminated, 
and are sold quite extensively in their natural shape for jewels, as they 
are small and brilliant. 

The ancients prized rock crystal much more highly than we do, 
because it answered them many of the purposes for which we now 
find glass cheaper and more suitable. Wine-glasses were made from 
it, though at great cost, a thousand dollars being considered a small 
price for one. Lenses of rock crystal were used to concentrate the 

143 



rays of the sun to procure heat for cauterizing wounds and to light 
fires, especially sacrificial ones. 

The following lines, adopted from an early Roman writer, refer 
to the latter custom : 

"Take in thy pious hand the Crystal bright, 
Translucent image of the Eternal Light; 
Pleased with its luster, every power divine 
Shall grant thy vows presented at their shrine; 
But how to prove the virtue of the stone, 
A certain mode I will to thee make known: 
To kindle without fire the sacred blaze, 
This wondrous gem on splintered pine-wood place, 
Forthwith, reflecting the bright orb of day, 
Upon the wood it shoots a slender ray 
Caught by the unctuous fuel this will raise 
First smoke, then sparkles, then a mighty blaze: 
Such we the fire of ancient Vesta name, 
Loved by th' immortals all, a holy flame; 
No other fire with such grateful fumes 
The fatted victim on their hearths consumes; 
Yet though of flame the cause, strange to be told, 
The stone snatched from the blaze is icy cold." 

Globes of rock crystal were found among the ruins at Nineveh, 
showing that the mineral was prized by that people. The Venetians 
carried the art of engraving on rock crystal to a high degree of per- 
fection, the effect of the figures being greatly enhanced by the addi- 
tion of foils of different colors. Rock crystal was also formerly stained 
many different colors to imitate other gems. The staining was per- 
formed by heating the stones to redness and immersing them in a dye 
possessing the desired color. The sudden change of temperature causes 
minute cracks over the surface, imperceptible to the naked eye, which 
absorb the coloring matter, and give the effect of complete coloration. 

The use of quartz balls for divination has already been referred 
to. Rock crystal has also long been credited with curative powers, 
especially of hemorrhage and dysentery. To cure the former it is 
applied to the bleeding part, and to cure the latter the powder mixed 
with wine is drunk. It has also been regarded a cure for headache and 
faintness if held in the mouth. In parts of Virginia it is supposed to be 
a cure for sties, the sty being rubbed with the crystal three times 
a day for three days. 

Many of the tribes of the North American Indians use pieces of rock 
crystal in their ceremonies, and regard them as having special magical 
powers. 

144 



The Hindoos regard rock crystal a specific for consumption, leprosy, 
and poisoning. It is known among them as "unripe diamond," and 
may be substituted in medicine for diamond. 

Amethyst. This term is applied to the violet or purple varieties 
of quartz. It is derived from two Greek words meaning " not to inebri- 
ate," and indicates the belief of the ancients that wine dr^nk from 
cups made of this mineral could never have any deleterious effect. 
All degrees of color are to be found in amethyst, from that only 
slightly tinted to that so dark as to be almost opaque. The color 
may be irregularly distributed, being sometimes in spots and again 
shading uniformly in the same crystal from light to dark. Of these 
colors the dark reddish-purple is the most highly esteemed, the paler 
stones being less sought after. A reason for this is to be found in the 
fact that by artificial light, especially if this contains yellow rays, pale 
stones lose their violet color and become a dull gray. The deeply 
colored amethysts, however, especially such as have been found in 
Maine, change to a wine color by artificial light, and thus their beauty 
is enhanced. Besides being of a deep purple color, a good amethyst 
should be perfectly transparent and uniform in hue throughout. The 
nature of the coloring matter of amethyst is not known. For a long 
time it was thought to be oxide of manganese; but as the color disap- 
pears on heating it is now believed to be a form of organic matter. 
It has been noticed in some places where amethyst is mined that the 
most deeply colored stones are at the surface, and that their color 
grows paler as the vein is followed downward. The cause of this 
phenomenon is not known. By partial heating the color of amethyst 
can be changed to yellow, and some of the so-called citrine is made 
in this way. 

Much opaque and coarse quartz has an amethystine color, but such 
is obviously of no value for gem purposes. The chief supply of the 
amethysts used for jewelry at the present time comes from Siberia 
and Brazil. ^The Siberian mines are located in the Urals in the vicin- 
ity of Mursinka and Alabashka. The amethyst occurs in cavities in 
granite, accompanied by beryl and topaz. Much of it is near the sur- 
face, and it is also found lying loose.' The Brazilian amethysts occur 
partly in cavities in a black eruptive rock (melaphyre), and partly 
as pebbles in the river gravels, accompanied by chrysoberyl, topaz, etc. 
Amethyst of gem quality is also found in Ceylon in gem gravels. 

In our own country amethyst occurs abundantly, but not often of the 
best quality for cutting. Some of the finest amethyst known has come 
from Oxford County, Maine, but only a few specimens have thus far 

145 



been obtained. Delaware and Chester counties, Pennsylvania, have 
furnished good amethysts, as well as Haywood County, North Caro- 
lina. One of the best known localities for amethyst in America is 
Thunder Bay, on the north shore of Lake Superior. Crystallized ame- 
thyst is found here in large quantities coating veins in the rock. 
While many of the crystals are highly colored they are not uniform 
in color and lack clearness, so that few good gems have been obtained 
here. 

Amethyst was much more highly prized in former times than now, 
probably on account of its greater scarcity then. A celebrated amethyst 
necklace, owned by Queen Charlotte, of England, which was valued at 
the time it was made at $10,000, would probably be worth hardly $500 
now. In spite of the comparative abundance of amethyst at the present 
time there is a constant demand for good stones, since no other gem 
affords its charming violet color. One dollar a carat is an average 
price for amethyst at the present day, and this value remains about 
the same even with an increase in size of the stones, as large amethysts 
are comparatively common. The step cut is usually adopted for ame- 
thyst, and is well adapted to it. Brilliants are, however, common, 
and the mixed cut also often gives a good effect. Amethyst was 
often worn in the Middle Ages as an amulet and preserver of the 
wearer in battle. It was supposed to be serviceable to persons having 
petitions to make to princes, and to be a preventive of hailstorms and 
locusts. It has also long figured as a pious or episcopal gem, being the 
stone which is regarded as imparting especial dignity or beauty to the 
property of the church. It is a gem especially sacred to St. Valentine, 
he being said always to have worn one. 

Rose Quartz. This form of quartz, the color of which is indicated 
by its name, is rarely of sufficient transparency to be prized as a gem. 
Cut, however, into various ornaments, it makes objects of considerable 
beauty. Its luster, instead of being glassy like that of other forms of 
quartz, is nearly always more or less greasy. The ingredient which 
gives it color is not known. * It is probably some organic matter, since 
the color disappears on heating and, unfortunately for the extended use 
of the stone, often fades considerably on exposure to light. Unlike 
other varieties of pheno-crystalline quartz, rose quartz has never yet 
been found in the form of distinct crystals. There are numerous locali- 
ties whence rose quartz of good color may be obtained, although it is not 
of so common occurrence as most other varieties of quartz. The best 
rose quartz in this country comes from Oxford County, Maine, and the 
Black Hills. Foreign localities are the Urals, Brazil, and Ceylon. 

146 



Smoky Quartz. This variety of quartz is often known as " smoky 
topaz," a misleading term, since the mineral is not topaz. As its 
name implies, its color is like that of smoked glass, all gradations occur- 
ring between a mere tinge to color so dark as to render the mineral 
practically opaque. The color often varies considerably in the same 
crystal, being darker and lighter in spots. The coloring matter is 
undoubtedly carbonaceous and organic in nature, for when a crystal is 
heated it gives off a smell of burning organic matter, and by heating for 
some length of time the coloring may be entirely burned out. At an 
intermediate stage in such heating the color becomes brown or yellow, 
and stones of this color are often cut as gems, and known by the name 
of "Spanish topaz" or "citrine." True citrine is, however, transparent 
quartz with a natural yellow color. The most remarkable crystals of 
smoky quartz known are some that were found in 1868 in a hollow in 
granite in a locality in the Canton Uri, Switzerland. About three thou- 
sand pounds of well-formed crystals were there found, the largest and 
best of which are preserved in the Berne Museum. The same region, 
and neighboring ones in the Alps, have also furnished large quantities 
of smaller crystals of notable perfection in form, and of fine quality. 

The next most important locality for smoky quartz is in the vicinity 
of Pike's Peak in the State of Colorado. Here the smoky quartz occurs 
in pockets in a coarse pegmatite accompanying amazon stone and other 
feldspars. Kunz mentions one crystal from this locality which measured 
four feet in length. Large, flawless pieces have been found, which have 
been cut into facetted stones weighing a pound or more. Alexander 
County, North Carolina, has also furnished much excellent smoky quartz. 
Large clear crystals and masses have been found at Auburn, Maine, one 
of these crystals being nearly two feet in length. These have furnished 
material for balls and other objects. Smoky quartz is sometimes known 
by the name of cairngorm stone, from its occurrence at Cairngorum, 
near Banff, in northern Scotland. The quartz from this locality was 
at one time widely distributed, and came to be regarded as the national 
gem of Scotland. The cairngorm stone occurs in connection with masses 
of granite, and is obtained by digging shallow pits or trenches in areas 
where considerable decomposition has taken place. The stone as used in 
jewelry is usually heated to give it a yellow color. Little of it is mined 
at the present time. 

Smoky quartz has the physical and chemical properties of rock crys- 
tal, by which it can be distinguished from other brown gems, such as 
axinite or brown diamond. It is usually cut in the form of the brilliant 
or the step cut. Being available in large, clear pieces, it is also used for 

147 



seals, brooches, penholders, etc. It exceeds rock crystal little if any 
in market price. 

Sagenitic Quartz. This form of quartz is variously known as " sage- 
nite," "fleche d'amour" (love's arrow), "hair stone," "needle stone," 
and if the included mineral be rutile, " rutilated quartz." These terms 
all refer to colorless crystallized quartz which is penetrated by hair-like 
crystals of other minerals. An illustration of the occurrence is given 
in the accompanying colored plate. Of the minerals so included rutile 
is the most common, but tourmaline, hornblende, epidote, goethite, and 
others occur. The inclusions have doubtless been formed in the quartz 
by crystallizing at the same time with it, the quartz in this case being 
the "host." The length of the included crystals may be considerable. 
Some of the rutilated quartz from Madagascar has single included crys- 
tals six inches long. The quantity of the included mineral may vary 
from a few long, scattered individual crystals to a multitude of short 
ones. For cut stones, pieces of the latter sort are usually preferred. 
Some of the prettiest effects are produced when the included mineral is 
rutile, and is sufficiently transparent to be of a blood-red color by trans- 
mitted light. By cutting suitable pieces of this sort into the form of 
hearts, the effect indicated by the term "love's arrow" can be prettily 
obtained. Often the included crystals cross each other nearly at right 
angles, thus giving the appearance of a network. It is on account 
of this appearance that the name sagenite, from the Greek sagene, a net, 
is given. Sagenitic quartz is obtained in various localities. Madagascar 
is perhaps the chief source of supply at the present time, much excellent 
material being obtained there. The rock crystal of Brazil is frequently 
sagenitic also. Several localities in the United States furnish sagenitic 
quartz, among them being North Carolina, Rhode Island, and California. 
Perhaps the finest specimens ever seen were gotten from some boulders 
found in the vicinity of Hanover, New Hampshire, in the years 1830- 
1850. Crystals of quartz containing hair-like crystals, or massive o:- 
scale-like inclusions of chlorite, are obtained in Japan, which are pre- 
pared for ornamental purposes simply by smoothing and polishing the 
natural crystal surfaces. 

" Cat's-eye" " Tiger-eye." These are forms of quartz containing 
fibrous inclusions, which, instead of being scattered, are massed together, 
so that upon a polished surface a sheen like that of silk is seen by 
reflected light. The term of Occidental cat's-eye is often applied to 
cat's-eye of this sort, in distinction from the Oriental cat's-eye com- 
posed of chrysoberyl. " Tiger-eye " is made up of somewhat coarser 
fibers than cat's-eye. It is of a golden yellow color, while the color of 

148 



cat's-eye varies from pale blue and pale green to reddish-brown. A blue 
variety occurring with the South African tiger-eye is known as " hawk's- 
eye." A piece of either of these minerals if cut en cabochon in a proper 
manner exhibits a band of light across it, changing in position when the 
stone is turned. The included fibrous mineral which gives the effect is 
asbestos. In the tiger-eye obtained from South Africa all gradations are 
found between crocidolite, which is a fibrous form of amphibole, and 
quartz, the tiger-eye being formed by a replacement of the crocidolite 
by the quartz. Thus the structure of the crocidolite is retained, but 
the stone has the hardness and luster of quartz. 

Cat's-eye comes chiefly from Asia, the Malabar Coast of India and 
the Island of Ceylon being the localities most prolific in it. In the latter 
locality it accompanies the Oriental or chrysoberyl cat's-eye. It is, how- 
ever, much less valuable than the latter. 

^Nearly all the tiger-eye used at the present time comes from South 
Africa. It is found in a range of quartzose schists called the Asbestos 
Mountains, located in Griqualand, and extending from Griquatown in a 
northeasterly direction toward the Transvaal. Griquatown is about one 
hundred miles west of Kimberley. Other localities northward along 
the Orange River also furnish tiger-eye. The mineral as found varies 
in color from blue to yellow, according to the degree of oxidation of 
the iron of the mineral. As already noted, the blue is called hawk's- 
eye. Owing to the quantity of the raw material available tiger-eye brings 
a low price, and has dropped out of fashion to a considerable extent. 
Twenty-five years ago it commanded a price of $6 a carat, being rated as 
high as turquois at the present day. Owing to the competition of two 
dealers at that time and the appearance of an immense supply, the price 
quickly fell to less than twenty-five cents per pound, and the demand 
for it almost ceased. ^ 

The cutting of tiger-eye is now largely carried on in Oberstein and 
vicinity at the great agate-cutting establishments. Ring and brooch 
stones, dishes, and vases are some of the objects made from it. 

Aventurine. Quartz known by this name contains inclusions, not 
in the form of fibers, but in that of scales of some bright mineral, such 
as mica or hematite. The quartz thus presents a spangled appearance. 
The spangles, according to the size of the included scales, may be 
coarse or fine. The choicest aventurine is that in which each scale 
gives a distinct reflection. The quartz base may be brown, red, yellow, 
or black, or rarely bluish or greenish in color, and the spangles usually 
silvery or golden. The aventurine most commonly used is of a reddish 
yellow color with a coppery sheen. Aventurine quartz resembles the 

149 



form of feldspar known as sunstone in appearance, but can easily 
be distinguished from it by its greater hardness. 

The best known localities for aventurine at the present time are 
the Ural and Altai mountains in Russia. In the former it occurs in 
the vicinity of Slatoust, in strata of mica schist, and in the latter not 
far from Kolivan. The aventurine from the latter locality is cut into 
large vases and dishes. One of the finest of these is to be seen in 
the Museum of Practical Geology in London. This vase was pre- 
sented by Nicholas I. to Sir Roderick Murchison in recognition of his 
services in investigating the geology of the Russian empire. Aventurine 
is said to be highly regarded in 4 "*China, the imperial seal being always 
made from it. India and several localities in Europe furnish aventurine ; 
but none of good quality has as yet been found in the United States. 
Owing to the facility with which it can be obtained in masses it is not 
used extensively except for making large ornamental objects. Together 
with sunstone it can be quite successfully imitated in glass. 

Crypto-crystalline quartz. The crypto-crystalline (obscurely crystal- 
line) varieties of quartz are many. The following may be named as the 
most important: Chalcedony, carnelian, sard, chrysoprase, prase, plasma, 
bloodstone, agate, onyx, sardonyx, jasper, basanite, flint, and hornstone. 
The distinctions between the different varieties are loose, and are differ- 
ently stated by different authorities. Some class agate, onyx, sardonyx, 
plasma, and carnelian as varieties of chalcedony, while others consider 
chalcedony a simple variety. 

The chalcedonic varieties of quartz agree in having a fibrous struc- 
ture and in being somewhat softer (hardness 6^) and somewhat lighter 
(specific gravity 2.6) than crystallized quartz. They also break with 
more difficulty than quartz, being very tough. The varieties differ 
among themselves chiefly in color. 

Chalcedony has a waxy luster, and is usually translucent rather 
than transparent. The transparent forms are known as "Oriental," 
the translucent as " Occidental " chalcedony. Common chalcedony has 
little color, shades of gray and blue being the most common, although 
other tints occur. It usually presents rounded surfaces which have 
grape-like, kidney-like, or stalactitic forms. It occurs coating other 
rocks or minerals, or lines cavities, or fills veins and clefts. It is never, 
so far as known, deposited in any other way than by percolating 
waters. At Tampa Bay, Florida, the waters containing chalcedony 
have penetrated corals and preserved them, often giving forms show- 
ing the shape of the coral outside and a cavity within. Throughout 
the " Bad Lands " of the West, clefts in the hills are often filled with 

150 



sheets of chalcedony, varying in thickness from that of thin paper 
to nearly an inch. These chalcedony veins ramify in all directions, 
and often extend for many rods without interruption. 

When the chalcedony is penetrated by branching forms of manganese 
or iron oxide, the forms known as " mocha stones " and " moss-agates " 
are produced. These are not due to vegetation, any more than the 
similar forms of frost on our window-panes. Moss-agates are found 
in numerous localities in the States of Utah, Wyoming, Colorado, and 
Montana. Kunz remarks that " no stone that is used in jewelry in the 
United States is cheaper, more beautiful, or more plentiful than the 
moss-agate." The best occur as rolled pebbles in the beds of streams. 
The name " mocha stone," sometimes applied to moss-agates, is either 
due to the fact that those first used came from Mocha in Arabia, 
or it is a corruption of the word moss-agate. The finest moss-agates 
now known come from 
India. A white variety of 
chalcedony, containing 
minute blood-red spots, 
is known as St. Stephen's 
stone. Chalcedony was 
formerly used much more 
and more highly prized 
than at the present time. 
It was especially employed 
for seals and rings, but 
also for plates, cups, and 
vases. These were often 
engraved in the most 
elaborate manner, the 

hardness and toughness 

. , , , . ,, 

oi the stone being well 

suited to this purpose. The sentiment of the stone is : " A disperser of 
melancholy." The name chalcedony is from Chalcedon, a city in Asia 
Minor, where the original chalcedony was found. This mineral was 
probably not like our modern chalcedony, but a green quartz. This 
chalcedony is mentioned in the Book of Revelations as one of the 
foundation stones of the Holy City. 

Carnelian is a red variety of chalcedony; sard a brown variety. 
All gradations between these shades of course occur, those of the 
reddish cast being the most common. The most highly prized color 
for carnelian is a deep blood -red, appearing darker red in reflected 

151 




Moss-agate, India. 



light. The lighter red and yellowish shades are less desirable, stones 
of these shades being known as " female " carnelians, while those of the 
darker shades are known as " male " carnelians. The colors are due 
to oxides of iron, and can sometimes be changed by heating. Thus, 
the yellowish and brownish carnelians, being colored by iron hydroxide, 
can be changed by heating to red, the water being driven off and iron 
oxide left. The heating may be done in the sun, or by some other 
slow means. Even olive-green stones are changed in India to red by 
this process. The color may also be introduced artificially, by allowing 
the stones to lie in a mixture of metallic iron and nitric acid, or of iron 
sulphate for a while. In this way the iron salt needed for the color- 
ing matter can be absorbed by the stone, and this be changed after- 
wards to oxide by heating. The best carnelians come from India, 
but good stones are also obtained in Siberia, Brazil, and Queensland. 
Carnelians are cut usually in oval and shield-like shapes. They were 
much employed by the ancients for intaglios, who believed them to 
have the power of preventing misfortune, curing tumors, preventing 
hoarseness, and strengthening the voice. They also insured victory in 
all contests save those of love. Used as a powder or worn in a ring 
carnelian was believed to prevent bleeding at the nose, and the belief 
survives to some extent to the present day. 

The name carnelian is, according to some authorities, derived from 
the Latin word caro, carnis, flesh, and refers to the color of the stone ; 
according to others, it is from the Italian word carniola, which has the 
same meaning. 

Sard, of typical brown color, is much rarer than carnelian, and 
possesses a higher value. The sardius mentioned in the Bible as form- 
ing one of the stones of the high priest's breastplate, was undoubtedly 
a carnelian. The name was derived from Sardius, a city of Lydia, 
whence fine carnelians are obtained. Sard occurs with carnelian and 
grades into it. The best sard should be of a deep brown color, shading 
to orange but with a reddish tinge by transmitted light. The color 
can be artificially produced by methods similar to those described 
below for coloring agates, but long and careful treatment is required. 
The sard was believed by the ancients to confer cheerfulness and cour- 
age and to be a preventive of noxious humors. 

Chrysoprase and prase are terms applied to an apple-green to bright 
green chalcedony, or compact, jasper-like form of quartz. Some author- 
ities, however, call the green chalcedony plasma, and restrict the term 
chrysoprase to the green compact quartz. The terms cannot be accur- 
ately distinguished. Most chrysoprase now in use comes from localities 

152 



in the province of Silesia, in Germany, where it occurs in thin layers 
and veins in serpentine. The green color is due to nickel oxide, 
which is present in the stone to the amount sometimes of one per cent. 
The first discovery of the stone is said to have been made by a Prussian 
officer in 1740. The stone was especially fancied by Frederick the Great, 
so that he had two tables made of it, and used it frequently in mosaics. 
The color fades with light and heat; but it is said can be restored 
by burying the stone in moist earth for a time. Beautiful chrysoprase 
comes from India, and there are a few localities in our own country 
where it is found, it being usually associated with nickeliferous deposits. 
The name chrysoprase comes from two Greek words, meaning golden 
leek, and refers to the color of the stone. By the ancients it was 
supposed to possess the virtues of the emerald though in less degree. 
They thought that it lost its color in contact with poison, and was an 
excellent cordial and stimulant. 

Plasma, as already stated, is a name applied to green chalcedony, 
or by some to green jasper. The name comes from the Greek for image, 
and shows that the stone was largely used for seals and other engraved 
work. Most of that known at the present time comes from India 
and China. 

Bloodstone is a variety of plasma containing spots of red jasper, 
looking like drops of blood. Another name for bloodstone, by which 
it was chiefly known by the ancients, is heliotrope. This name is 
derived from two Greek words, meaning " sun turning," and refers 
to the belief that the stone when immersed in water would change 
the image of the sun to blood-red. The water was also said to boil and 
overflow the containing basin. As late as the middle of the seventeenth 
century bloodstone was used as a cure for dyspepsia, and when powdered 
and mixed with honey was considered a remedy for tumors. If rubbed 
with the juice of the heliotrope it was supposed to render its wearer 
invisible. It was often used for stopping the flow of blood, either by 
touching the bleeding spot with it, or by wetting the stone in water 
and holding it in the hand. It was also often used for carvings 
representing the head of Christ, one fine specimen of such work being 
preserved in the Field Columbian Museum. The ancients had a tradition 
that the stone originated at the crucifixion of Christ, from drops of blood 
drawn by the spear thrust in his side, falling on a dark green jasper. 
The stone takes a beautiful polish. To be of the best quality, it should 
have a rich, dark green color, and the red spots should be small and 
uniformly distributed^ The supply is obtained almost wholly from India, 
especially from the/'Katniawar Peninsula west of Cambay, whence agate, 

153 



carnelian, and chalcedony are also obtained. Fine examples have also 
come from Australia and a few from Brazil. 

Agate differs from other forms of quartz in being made up of 
minute layers, which are variegated in color. The colors may appear 
in the form of bands or clouds. The banded agates appear to be 
made up of parallel layers, sometimes straight, but more often wavy 
or curved in outline. These layers or bands differ in color from 
one another, exhibiting shades of white, gray, blue, yellow, red, brown, 
or black. To the naked eye they appear to vary in width from the 
finest lines to a width of a quarter of an inch or more. In reality, all 
the bands visible to the naked eye are made up of finer ones, to be seen 
only with the microscope. Thus in a single inch of thickness of agate 
Sir David Brewster, using the microscope, counted seventeen thousand 
and fifty layers. Besides differing in color, the layers differ in trans- 
parency and porosity, and these properties add to the variegated appear- 
ance of the agate. 

On account of their beauties of color and outline, agates have been 
known and prized from the earliest times. They are mentioned by many 
of the ancient Greek writers, and the name agate is a corruption of the 
name Achates, a river in Sicily, whence the first stones of this kind used 
by the Greeks were obtained. This and neighboring localities continued 
to be the source of supply until the fifteenth century, when agates were 
found to occur in large quantities near Oberstein and Idar, on the banks 
of the River Nahe, in the duchy of Oldenburg. 

The industry of cutting and polishing agates on a large scale was 
soon established there, and these places are to this day the center of the 
agate industry. The agates used most extensively at the present time 
are not, however, those found about Oberstein, but come from a region 
about one hundred miles in length, extending from the Province of Rio 
Grande do Sul in Southern Brazil into Northern Uruguay. The agates 
in this region, first discovered in 1827, so surpass in size and beauty 
those from any other known locality, that they form at the present time 
almost the only source of supply. They are shipped in large quantities 
as ballast to Oberstein and Idar, and here the work of cutting, polishing, 
and coloring them is performed. The discovery that the attractiveness 
of agates could be enhanced by artificial coloring was made about the 
beginning of the nineteenth century. The natural colors are rarely of a 
high order, being often only variations of white and gray, or dull yellows 
and reds. Through the difference of porosity of the different layers, 
however, and the consequent different absorption of coloring ingre- 
dients, colors can be artificially introduced which produce lasting and 

154 







422 



Banded Agate (Brazil). 



AGATE. 

Banded Agate (Lake Superior). 
Moss Agate. 



COPYRIGHT 1901, BY A. W. MUMFORD, CHICASO. 



Clouded Agate. 



pleasing effects. Most agate used for ornamental purposes at the present 
time is, therefore, artificially colored. The method of coloring is to boil 
the stone in honey for a number of days, or even weeks, according 
to the porosity of the agate and the color desired, then to immerse it 
in hot sulphuric acid. The acid chars to a brown or black the carbon 
of the honey which has been absorbed by the stone. Various coloring 
ingredients, such as oxides of iron, salts of nickel, Prussian blue, etc., 
may be added to the liquids employed at some stage of the process, 
and thus different colors be obtained. 

Agates of considerable beauty, though not of great size, are found in 
many places in the United States. Those of Agate Bay, Lake Superior, 
have rich colors, and make attractive charms and- other ornaments. 
Agates are found in the beds of many streams in Colorado, Montana, 
and other regions of the Rocky Mountains. They occur all along the 
Mississippi River, especially in Minnesota, also along the Fox River, Illi- 
nois, in the trap rocks along the Connecticut River, and on the coast of 
California. While many of these agates are of great beauty, their use 
and sale is not likely to be anything more than local, since the Brazilian 
agates can be supplied so cheaply from Germany. 

The layered structure of agates is due to successive depositions 
of silica by water flowing through cavities in rocks. Rising and falling 
alternately through the rocks the water leaves a mark of each advance 
or retreat in the form of an additional layer deposited upon the interior 
walls of the cavity. Agates, therefore, grow from the outside inward. 
The process may go on until the cavity is entirely filled or may cease 
at any time. If the cavity is small and nearly circular, and becomes 
entirely filled, the kind of agate known as "eye-agate" is produced. 
If water remains in the cavity for some time crystals, such as are some- 
times seen, will be formed. The nodule of silica or agate formed by 
the percolating waters is harder and more resistant than the surround- 
ing rock. Hence it remains after the surrounding rock has been worn 
away. We can thus understand why agates should be found, as they 
usually are, on sea or lake beaches, or in the beds of streams. 

The different colors seen in the natural agates are produced by traces 
of organic matter or of oxides of iron, manganese or titanium contained 
in the waters which formed them. 

Agates are not used as extensively as they once were for ornamental 
purposes. In the years of 1848-50 agate jewelry was very fashionable, 
and was extensively worn. At the present time, however, the principal 
use of agate in jewelry is for breastpins and watch-charms. For orna- 
mental purposes it is used in pen-holders, knife-handles, and vases. Its 

155 



use for large marbles was once quite common, but glass marbles of the 
same size, and still called "agates," are now generally substituted. In 
fine mechanical work, such as bearings for delicate instruments, and in 
tools for polishing and grinding, agate is still extensively used. 

Various curative properties were formerly attributed to the agate, 
belief in some of which still survives, especially among Mohammedan 
peoples. It was regarded as a cure for insanity, and as a preventive of 
skin diseases. It symbolized health and wealth, and was supposed to 
render its wearer gracious and eloquent. 

Onyx and sardonyx are varieties of agate in which the layers are in 
even planes of uniform thickness. This structure enables the stone to 
be used for engraving cameos. As is well known, these are so made that 
the base is of one color and the figure of another. This art of making 
cameos reached a high degree of perfection among the Romans, and 
many superb examples of it have come down to us. The word onyx 
means a nail (finger-nail), and refers to some fancied resemblance, per- 
haps in luster, to the human nail. Sardonyx is a particular variety 
of onyx in which one of the layers has the brown color of sard. Other 
kinds of onyx are those known as chalcedonyx and carnelionyx, in refer- 
ence to the color of the intervening layers. So-called Mexican onyx is 
composed of quite a different mineral from the onyx here considered, it 
being made up of calcite rather than quartz. Hence Mexican onyx can be 
scratched easily with a knife, while quartz onyx cannot. Mexican onyx 
has, however, the banded structure of quartz onyx, and it is in allusion 
to this undoubtedly that the name has been applied. A sardonyx upon 
which Queen Elizabeth's portrait was cut constituted the stone of the 
famous ring which she gave the Earl of Essex as a pledge of her friend- 
ship. It will be remembered that when the earl was sentenced to death 
he sent this ring to his cousin, Lady Scroop, to deliver to Elizabeth. 
The messenger by mistake gave it to Lady Scroop's sister, the Countess 
Nottingham, who being an enemy of the earl's did not deliver it to the 
queen, and the earl was executed. On her deathbed the countess is said 
to have confessed her crime to the queen, who was so infuriated that she 
shook her, saying "God may forgive you, but I cannot." 

In the Middle Ages sardonyx was used as an eyestone, and is employed 
in Persia to this day for the cure of epilepsy. It was supposed by the 
ancients to be an entirely different stone from the onyx. To it was ascribed 
the property of conferring eloquence upon its wearer, and it especially sym- 
bolized conjugal bliss-. It is mentioned in Revelations as one of the stones 
forming the foundations of the Holy City. Onyx and sardonyx which 
come from the Orient are esteemed of much higher value in trade at the 

156 




41)9 



QUARTZ (obscurely crystalline). 



Bloodstone, polished (India). 
Tiger Eye, polished (South Africa). 



Chrysoprase (Silesia). 
Agate and Carrielian, polished (Lake Superior). 



Jasper (Germany). 

Kibbon Jasper, polished (Siberia). 



present time than those prepared in Germany. There seems to be no 
good reason for this, however, as the latter can be so skillfully made 
that it is impossible to distinguish them from the Oriental stones. 

Jasper includes in general nearly all varieties of impure, opaque, 
colored, crypto-crystalline quartz. In color it may be red, yellow, green, 
brown, bluish, and black. To many of the pebbles found on almost any 
sea or lake shore, or in the beds of streams, the name jasper may prop- 
erly be applied. If it occurs banded, that is, in stripes of different colors, 
it is known as ribbon jasper. The different colors of jasper are due 
to different impurities which it contains. These may be clay, iron 
oxides, or organic matter, and at times reach a quantity as high as 
twenty per cent. The color often varies irregularly in a single stone, 
giving different effects, and sometimes imitating paintings. Jasper 
which can be used in the arts is very widely distributed. Good red 
jasper is obtained in Breisgau, and near Marburg in Germany. Much 
brown jasper comes from Egypt. What is known as " Sioux Falls 
jasper," from Sioux Falls, South Dakota, is chiefly of a brown color. 
This stone was highly prized by the Indians for its color, and is the 
"jasper" referred to by Longfellow in Hiawatha: 

"At the doorway of his wigwam 
Sat the ancient Arrow-maker 
In the land of the Dacotahs, 
Making arrow-heads of jasper, 
Arrow-heads of chalcedony." 

The yellow jasper used for mosaics comes chiefly from Sicily, but 
as good could be obtained in many places in our own country. The 
green jasper of the present time is obtained chiefly in the Urals, and 
is to a considerable extent worked there into ornamental pieces. The 
Chinese^ prize green jasper highly, the seal of the emperor being made 
from it. Some jasper of a bluish shade is found in nature; but that 
of a deep blue tinge is always artificially colored by Prussian blue. 
It is then sometimes known as " false lapis "; that is, false lapis lazuli. 
Kibbon jasper is found in Saxony, but chiefly comes from the Urals. 
The qualities which make jasper of use in the arts are its color, 
opacity, and capacity for taking a polish. At the present time it 
is not much used except for mosaic work, and for small boxes, vases, 
and dishes. The ancients, however, prized it highly and used it exten- 
sively. It is one of the stones prescribed in the Book of Exodus to be 
worn in the ephod of the high priest, and also forms one of the gates 
of the Holy City, as described by St. John in Revelations. It is prob- 
able that the jasper referred to in these instances was of a dark green 

157 



color, as this was the tint most prized in early times. Green jasper 
was also called emerald in some instances. The banded varieties were 
much used for cameos, specimens of which are still extant. By taking 
advantage of the colors of the different layers, colored objects were 
made, such as one which shows the head of a warrior in red, his helmet 
green, and breastplate yellow. 

Jasper worn as an amulet was regarded a preventive of sorrow, and 
mottled jasper suitably engraved was believed to protect its wearer from 
death by drowning. It was a charm against scorpions and spiders, and 
strengthened the chest, lungs and stomach, according to beliefs held in 
the Middle Ages. 

Basanite, also known as Lydian stone, or touchstone, is chiefly used 
for trying the purity of metals. Its value for this purpose depends on its 
hardness, peculiar grain, and black color. Different alloys of gold give 
different colors on the stone, and thus enable one to determine the fine- 
ness of the gold. Also, if an object is plated, by giving it a few strokes 
on the stone, the different color of the gold and base will be revealed. 
Basanite is a black variety of crypto-crystalline quartz, differing from 
jasper in being tougher and of finer grain, and from hornstone in not 
being splintery. 

Flint is likewise an opaque quartz of dull color. It differs from 
jasper in breaking with a deeply conchoidal fracture and a sharp 
cutting edge. It is also often slightly transparent, and has a some- 
what glassy luster. These properties have led to its extensive use 
by the Indians and by nearly all primitive peoples for the manufac- 
ture of weapons and implements. Hornstone is more brittle than 
flint, and has a splintery rather than a conchoidal fracture. A num- 
ber of other subvarieties of crypto-crystalline quartz occur, but they 
are not important as gems. 



158 










477 



Precious Opal in matrix (Queensland). 
Precious Opal (New South Wales). 



OPAL. 

Wood Opal (Idaho). 

Precious Opal (New South Wales). 

Prase Opal (Germany). 



Precious Opal (New South Wales). 
Fire Opal in matrix (Mexico). 



OPAL 

"The opal, when pure and uncut in its native rock," says Ruskin 
in his lecture on Color, " presents the most lovely colors that can be 
seen in the world, except those of clouds." 

While not all may share the great art critic's preference for uncut 
stones, there are few probably who do not join heartily in admiration 
of the brilliant gem from whose depths come welling up tints of so 
varied hue that we appropriately speak of them as colors at play. 
Regarding these colors Ruskin says further : " We have thus in nature, 
chiefly obtained by crystalline conditions, a series of groups of entirely 
delicious hues ; and it is one of the best signs that the bodily system 
is in a healthy state when we can see these clearly in their most 
delicate tints, and enjoy them fully and simply with the kind of 
enjoyment that children have in eating sweet things. I shall place 
a piece of rock opal on the table in your working -room; and if 
on fine days you will sometimes dip it in water, take it into sun- 
shine, and examine it with a lens of moderate power, you may always 
test your progress in sensibility to color by the degree of pleasure it 
gives you." 

The opal is indeed one of the most fascinating of gems; yet often 
elusive, and at times disappointing. Of its freaks and foibles strange 
stories are told. Gems of brilliant quality sometimes lose their hues 
never to regain them, and others previously dull and lusterless become 
radiant. Professor Egleston, of New York City, once related that 
a bottle of cut opals given him by a prominent jewelry firm because 
they had lost their color, after remaining in his cabinet for a time 
regained their brilliancy and retained it. But to have opals regain 
their color is, unfortunately, far less usual than for them to lose it. 
The gem often exhibits brilliant colors when wet either with water 
or oil that disappear when it is dry. Taking advantage of this 
peculiarity dishonest dealers often keep opals immersed until just 
before offering them for sale. Purchasers of opals of this sort 
have good reason to believe the superstition commonly attached to 
the opal that it is an unlucky gem. Some authorities, however, trace 
the origin of the superstition to Sir Walter Scott's novel "Anne 

159 



of Geierstein," in which the baleful influence of the opal plays a promi- 
nent part; and it is stated that within a year of the publication of the 
book the price of opals declined fifty per cent in the European market. 
Even if the superstition did not originate in either of these ways, it was 
probably from a source quite as trivial, and it should prevent no one 
from enjoying the pleasure to be derived from the beauties of this gem. 

Chemically, opal is oxide of silicon, with varying amounts of water, 
the variation being from 3 to 9 per cent. It is, therefore, closely 
allied to quartz, but differs physically in being softer and not as heavy. 
Further, it never crystallizes, and is soluble in caustic potash, which 
quartz is not. It is infusible, but cracks and becomes opaque before 
the blowpipe. In sulphuric acid it turns black, on account probably 
of the organic matter it contains. 

Its hardness is sometimes as low as 5.5, though generally 6. Its 
specific gravity is from 1.9 to 2.3. On account of its relative softness 
a cut opal often does not retain its polish well, and requires frequent 
smoothing. Opals, when first taken from the ground, are often softer 
even than the above, and for this reason it is usual and desirable 
to allow them to harden, or " season," as it is called, for some time 
after quarrying before they are polished. 

Opal, as a mineral, is quite common, so that no one need suppose 
because he has specimens labeled " opal " in his collection that he has 
as many precious stones. It occurs in many varieties; and, especially 
if it contains foreign matter, in many colors. Nearly all silica deposited 
by hot waters is in the form of opal, so that the geysers of Yellowstone 
Park build up cones of opal and fall into opal basins. This particular 
form of opal is known as geyserite, and it is often differently colored 
by different ingredients. 

Wood is often preserved by silica in the form of opal, the siliceous 
waters taking away the wood and replacing it by opal, grain by grain, 
with such delicacy and accuracy that the structure of the wood is per- 
fectly maintained. The minute shells which diatoms make consist 
of opal, and when these dead shells accumulate to form deposits 
of some extent we call the powdery substance tripoli, and use it for 
polishing silverware and other metals. Other varieties of opal include 
hyalite, a variety looking like transfixed water, so clear and colorless 
is it; hydrophane, a translucent variety which sticks to the tongue and 
becomes nearly or quite transparent when soaked in water ; cacholong, 
a porcelain-like variety ; and menilite, a concretionary variety. 

Common opal varies from transparent to opaque, being most often 
translucent, and sometimes exhibiting the peculiar milkiness of color 

160 



which we call opalescence. It has sometimes a glassy, but often a waxy, 
luster, the latter when pronounced giving rise to the varieties known 
as wax opal and resin opal. When opal has the banded structure 
of agate it is known as opal-agate ; when it has the color of jasper, 
as jasper-opal; and when that of chrysoprase, as prase-opal. But none 
of these varieties is used in any quantity as gems. This distinction 
is reserved almost wholly for the variety known as noble or precious 
opal. This is opal which exhibits a play of colors. No essential chem- 
ical or physical distinction between noble opal and other varieties 
is known. In a large vein of opal portions will exhibit the play 
of colors and the remainder will not; but why the difference has not 
yet been determined. The uncolored opal is known by the Australian 
miners as "potch," while that which is precious is known as "colors." 
The origin of the varied coloring, i. e., the iridescence, is not positively 
known. Some regard it as due to interspersed layers containing differ- 
ent percentages of water, which break up the rays of light somewhat 
as a prism does, while others think that minute cracks and fissures 
through the stone furnish surfaces from which the rays are reflected 
in different colors back to the eye. Some opals which are dull and 
lusterless when dry, exhibit considerable play of color when immersed 
in water, and this fact seems to favor the first theory of the cause 
of the iridescence, but the subject is not understood. The character 
of the play of colors differs in different opals, and this gives rise 
to different varieties. The true noble opal has the color quite uni. 
formly distributed. When the color appears in flashes chiefly of red 
and yellow, the stone is known as fire opal; of blue, as girasol; apd 
chiefly of yellow, as golden opal. When the patches of color are small, 
angular, and uniformly distributed the stone is called harlequin opal, and 
if these are long and somewhat parallel, flame opal. These colors 
are not, of course, inherent in the stone, its color varying from color- 
less to opaque - white. The black opals sometimes seen are usually 
of artificial origin, being made by soaking ordinary opals in oil and 
then burning the oil. The brilliancy of the stone is thus increased ; but 
it is made fragile and liable to lose color. Any opal, however, may 
lose its play of colors on being heated too highly. It is the variety 
and brilliancy of the changing colors which give to opal nearly all its 
desirability as a precious stone, for the qualities of hardness, trans- 
parency, and rich body color, which give to most other gems their 
value, are lacking in it. But, together with the beauty of its changing 
colors, opal possesses an advantage over all other gems in that it can- 
not be successfully imitated. It is said that the Romans were able to 

161 



make artificial opals closely resembling the real ; but the art has never 
been fully recovered, and we may hope it never will be. Hence, however 
much danger there may be in buying an opal that has not been properly 
" seasoned," or one that may lose its play of color, the purchaser may 
at least be sure he has an opal and not an imitation. The stones are 
usually cut in the cabochon form, this cutting being found to bring out 
their brilliancy better than any facetted form. The brilliancy of the 
stone may be increased in setting by giving it a backing of mother-of- 
pearl, or black silk. When a number of opals are placed together they 
seem to borrow brilliancy from one another, a fact which is taken ad- 
vantage of in settings by placing a number together, and also by opal 
dealers to dispose of inferior stones by grouping them with good ones. 
For this reason when opals are purchased they should be examined sep- 
arately. The value of opals depends almost wholly on the brilliancy of 
their coloring and their size. Stones without the play of colors are prac- 
tically worthless, while stones of ten to twenty carats' weight, with bril- 
liant coloring, may bring several hundred dollars. The most highly 
valued opals have long come from the mines oj: Czernowitza, in northern 
Hungary. These opals are often known as Oriental opals, from the fact 
that in early days they were first purchased by Greek and Turkish mer- 
chants, and by them sent to Holland. There are, however, no known 
localities in the Orient where precious opals are found. The rock in 
which the Hungarian opals occur is eruptive, and of the kind known 
as andesite. It is considerably decomposed, and the opal occurs in clefts 
and veins. There is little doubt that it was from these mines that the 
Romans obtained the opals known to them, and the output has been quite 
constant since. It is said that the Hungarian opals are less likely to 
deteriorate than any others. Still the danger of deterioration is not great 
in any opal. The other important countries from which precious opals 
are obtained, are Mexico, Honduras, and Australia. The Mexican opals 
are mostly of the fire opal variety. They are mined in a number of the 
States of the Republic Queretaro, Hidalgo, Guerrero, Michoacan, Jalisco, 
and San Luis Potosi. The oldest mines are in the State of Hidalgo, 
near Zimapan, where the opal occurs in a red trachyte. Most of the 
Mexican opals on the market at the present time, however, come from 
the State of Queretaro, where mining for them is conducted on an 
extensive scale. The opal here occurs in long veins, in a porphyritic 
trachyte, and is mined at various points. The stones are cut and 
polished by workmen in the city of Queretaro, who use ordinary grind- 
stones and chamois skins for the work, and are said to receive an aver- 
age wage of twenty-three cents a day. The ^Honduras opals reach 

162 




O 
00 



foreign markets but rarely and usually uncut. The mines are chiefly in 
the western part of Honduras, in the Department of Gracias, but good 
opals also occur in the mountains on the boundary between Honduras 
and San Salvador. They are little worked, but there is no doubt that 
extensive deposits exist which might afford a good supply of gems if 
they were properly exploited. The Australian opals come from several 
localities, the most prominent at the present time being White Cliffs, 
New South Wales. The matrix is a Cretaceous sandstone, which has 



> y/ , s **?;f* C * - 




Opal mines, White Cliffs, New South Wales 

been permeated by hot, volcanic waters. Shells, bones, and other fossils 
are found here entirely altered to precious opal, making objects of great 
beauty. In 1899 opals to the value of $650,000 were sold from this 
single region. There is no doubt that the present popularity of the 
opal is due to some extent to the supply of beautiful stones which has 
come from these mines, at prices one-third to one-tenth those of the 
Hungarian stones. Other localities in Australia whence precious opals 
are obtained are places on the Barcoo River and Bulla Creek, Queens- 
land, and occasional finds in West Australia. 

No localities in the United States yielding precious opals in any 

163 



quantity have yet been discovered. Some good stones have been cut 
from an occurrence in Idaho, and some other minor finds have been 
made, but they possess little commercial importance at present. 

Opal does not seem to have been extensively known or used by 
the ancients, although the Romans prized it highly, and ascribed to it 
the power of warning against disaster. They named it the Paideros, or 
Cupid, and regarded it the perfection of beauty. Pliny describes it as 
combining the fire of the ruby, the purple of the amethyst, and the sea- 
green of the emerald, all shining together in an indescribable union. 
The Roman senator Nonius owned one set in a ring, which was said to 
be valued at nearly a million dollars. History records that for refusing 
to sell the stone to Mark Antony he was sent into exile. This stone was, 
however, no larger than a hazelnut, and would probably be worth hardly 
a hundred dollars at the present day. The next most famous opal in 
history is one that was owned by the Empress Josephine, and called 
"The Burning of Troy," on account of the brilliancy of the flames 
which shot forth from its depths. The present whereabouts of neither 
of these gems is known. A large Mexican opal, now in the Field 
Columbian Museum, is carved in the image of the Mexican sun-god, 
and has a setting of gold representing the diverging rays of the sun. 
This gem is very ancient, and is believed to have been kept in a Persian 
temple. To the opal was assigned, in the sixteenth century, the power 
of making its wearer a general favorite, enhancing the keenness of his 
sight, and shielding him from suicide. The name opal is from the Greek 
word for eye, and shows the esteem in which the gem was held for treat- 
ing diseases of that organ. It was also supposed to have the virtues of 
all the stones whose colors it showed. It was believed to stimulate the 
heart, cheer the despondent, and preserve from contagion. Like the tur- 
quois, its color was supposed to change if its wearer grew ill, and regain 
it when he recovered. It symbolized hope also. The belief in its bring- 
ing ill-luck is of more modern origin, and confined to Occidental peoples. 

Possession of a black opal is regarded in India, at the present time, as 
productive of good fortune. 



164 



JADE 

Jade is a term applied in general to a tough, fibrous mineral of a 
greenish color having the composition of a pyroxene or amphibole. 
Until recently the mineral was supposed to form a single species, but 
it is now known that at least two species are grouped under this title. 
One of these is a form of pyroxene, and is known as jadeite, the other 
is a form of amphibole, and is named nephrite. Further, the term is 
often used to include any tough green stone having a hardness between 
6 and 7 and taking a good polish, since such rocks or minerals are often 
carved by people who use true jade. Jadeite is a mineral of definite 
composition, it being a silicate of soda and alumina. The percentage 
composition of pure jadeite is. silica 59.4 per cent, alumina 25.2 per 
cent, and soda 15.4 per cent. Its hardness is a little below that of 
quartz, or between 6.5 and 7, but its extreme toughness makes it often 
seem harder than this. It is a rather heavy mineral, its specific gravity 
being 3.35. In color it varies from nearly white to nearly emerald-green. 
The white varieties sometimes contain spots of bright green, supposed to 
be due to chromium. The mineral does not crystallize, but is known from 
its optical properties to be either monoclinic or triclinic. It does not 
occur transparent, but has a peculiar translucency or subtranslucency not 
unlike that of horn or fine porcelain. It has a fibrous to granular 
structure readily seen under the microscope, and a splintery fracture. It 
is very tough. Jadeite fuses readily before the blowpipe to a trans- 
parent, blebby glass, and colors the flame yellow, thus differing from 
nephrite, which is almost infusible. The term chloromelanite is applied 
to a dark green to black jadeite containing considerable iron. 

Objects of jadeite carved in prehistoric times are found abundantly 
in Europe, Asia, America, and Africa, but only a few of the original 
localities whence it was obtained are now known. ^The most important 
locality known at the present time is in Upper Burmah in the vicinity 
of Mogoung. The jadeite occurs in boulders embedded in a reddish 
yellow clay in the valleys of tributaries of the Dschindwin River. The 
boulders are mined by digging shallow pits after the fashion of the Bur- 
mese miners, as many as a thousand men often being employed in this 
work. The miners break the boulders by heating, and when pieces of 

165 



quality suitable for cutting are found, they are either laid aside to sell to 
caravans which come to the mines for this purpose from China, or are 
turned over to native artisans, who reduce them to desired shapes by 
sawing them with steel wire strung on a bamboo bow. The jadeite 
from this locality is commercially distributed all over China, where it is 
held in high esteem, and commands a high price. Bauer states that he 
saw a piece containing less than three cubic feet which was valued at 
$50,000. The jadeite of milk-white color is that most highly esteemed, 
although that with bright green spots is also considered of superior value. / 

Nephrite is a variety of amphibole much resembling jadeite in color, 
hardness, and texture. It is, however, of somewhat lower specific gravity 
than jadeite, ranging as it does from 2.96 to 3.1, and it fuses with much 
greater difficulty. Under the microscope a section shows a finely fibrous 
character differing from that of the broad fibers or granules of jadeite, 
and the optical characters throughout are those of an amphibole rather 
than of a pyroxene. In composition nephrite is a silicate of calcium and 
magnesium, having the theoretical percentages, silica 57.7, magnesia 28.9, 
and lime 13.4. A little alumina, iron, and soda are often found combined 
with the above. Nephrite has the glistening luster and semi-translu- 
cency of jadeite, and like that mineral breaks with a splintery fracture. 
It is not attacked by acids. It does not occur in distinct crystals. 

<^The most important locality for nephrite at the present time is 
Turkestan, where it occurs in the Karakash Valley in the Kuen Lun 
Mountains, and at other points in the same range. In these localities it 
forms layers in gneiss and amphibole schists. It is very pure and trans- 
lucent. Some of the mines have been worked for over two thousand years. 
//Nephrite of excellent quality also occurs in eastern Siberia in the 
beds of the Onot and Chara Jalga rivers. It occurs here as boulders, 
one of which is described as being twelve feet in length and three feet 
in width; it is also found in place. A canopy thirteen feet in height 
has been made for the tombs of the present Czar and Czarina of Russia 
of nephrite from this locality. 

In New Zealand nephrite occurs in seve^l localities on the west coast 
of South Island, and is used extensively by the Maoris for fashioning into 
weapons and ornaments. 

Boulders of nephrite have also been found in river beds in Alaska. 
In several river beds of Europe nephrite is found as pebbles, and it occurs 
in place in the Zabten Mountains in Silesia, but none of these localities 
affords an important source of supply. 

Jade, including both jadeite and nephrite, though still highly prized 
by the Chinese and other peoples of Asia, is little used by Europeans at 

166 



the present time. Among early man, however, in Europe, Asia, America, 
and Africa, the use of jade seems to have been well-nigh universal. Orna- 
ments and utensils of this stone are found among the remains of the lake 
dwellers of Switzerland, the ancient peoples of France, Mexico, Central 
America, Greece, Egypt, and Asia Minor. The remarkable similarity 
in the material from which these objects are made, as well as their 
resemblance in form, has led some authorities to conclude that they 
came from a single region, and indicate a migration of people from one 
locality and a commerce in this stone. If the evidence to this effect 
were sufficiently convincing it would make possible many deductions 
regarding the peopling of the globe of which we have as yet little certain 
knowledge. Those who oppose the view of the distribution of jade from 
a single source declare that the stone was found in each different coun- 
try, and was similarly selected at a certain stage in the development of 
each people. This view seems to be supported by the fact that the 
so-called jade objects of different peoples are not composed exclusively 
of the two minerals above mentioned, but include any stone having about 
the same physical characters and color. Still, the two minerals jadeite 
and nephrite largely predominate. The two are equally used by the 
Chinese of the present day, who do not seem to distinguish between them. 
Their name for jade is Yu, or Yu-shih (Yu-stone). In general it has been 
found that the peoples nearer the equatorial zone of the earth use more 
jadeite, and those nearer the poles more nephrite, but whether this use 
is anything more than accidental cannot be said. 

The name jade is from the Spanish piedra de hijada, " stone of the 
loins," and was given by the Spaniard Monardas in 1565 to the jade 
brought from Mexico and Peru because these stones were reputed to be 
of value in kidney diseases. For this purpose it was much worn as an 
amulet, or taken internally. The name was given the Latin form lapis 
nephriticus by Clutius in 1627, and hence comes the word nephrite. 
Jade is also called ax-stone because of the amount of it used in making 
these objects. 

The Aztecs applied the name chakhihuitlio a greenish stone which 
they used extensively and prized highly. This in some instances proves 
to be jade and in others turquois. It is probable that much of the 
so-called emerald of ancient writers and historians, both of Europe and 
America, was jade. 



167 



DIOPSIDE 

This variety of pyroxene affords transparent green stones, which, may 
resemble in color chrysolite or green tourmaline. Diopside is common as 
a rock-forming mineral, but is obviously of use for gem purposes only 
when occurring in large, transparent crystals. The three localities where 
material of the latter sort is chiefly obtained are the Ala Valley in the 
Piedmont region of Italy, the Zillerthal in the Tyrolese Alps, and De 
Kalb, St. Lawrence County, New York. The first and third localities 
afford light green stones, the second those of a dark bottle-green color. 
They are cut generally as brilliants, and while not extensively used, make 
satisfactory stones. Those obtained from De Kalb afford gems up to 10 
carats in size. Diopside may be distinguished from gems of other min- 
erals of the same color by its lack of dichroism, this being a characteristic 
of this pyroxene. From glass it differs in being doubly refracting. 
Its system of crystallization is monoclinic. Its hardness is 6 ; specific 
gravity, 3-3.6. In composition diopside is a silicate of lime and mag- 
nesia, with a small amount of iron, its color growing darker with more 
iron. It has a prismatic cleavage, not often strongly enough developed, 
however, to interfere with cutting the mineral. Its luster is somewhat 
oily like that of chrysolite. The appearance of crystals from the Ala, 
accompanying essonite, is shown in the colored plate. 



168 



HYPERSTHENE AND BRONZITE 

These minerals, belonging to the pyroxene group, are employed in 
jewelry when, on account of a fibrous structure or a regular arrangement 
of inclusions, they exhibit a chatoyant effect. They do not afford trans- 
parent stones, but are cut en cabochon to make cat's-eyes and give other 
schillerizing effects. 

The color of hypersthene is usually a dark bronze, so opaque as to 
approach a metal in luster. The light which plays over it is copper-red in 
color, and very brilliant in a good stone. The cause of the chatoyancy 
is supposed to be countless crystals of the oxide of titanium, known as 
brookite, which are arranged in regular order in the stone. The stone 
must be cut with reference to the direction of these in order to give the 
chatoyant effect. 

The hypersthene used for this purpose comes almost exclusively from 
the Island of Paul on the coast of Labrador. Here it occurs together 
with labradorite as shore pebbles, and it may also be quarried from neigh- 
boring cliffs. For cutting, a sound piece without flaws must be used, 
and it is often necessary to break a number of fragments before a suit- 
able one can be found. Yet the supply of material is so abundant and the 
demand comparatively so limited that the stones do not command a high 
price. 

The hardness of hypersthene is 5-6; its specific gravity 3.4-3.5. It 
fuses before the blowpipe to a black enamel, and is partially decomposed 
by hydrochloric acid. Its name comes from two Greek words meaning 
very tough. It is a common constituent of eruptive rocks, usually in 
small crystals. Its system of crystallization is orthorhombic. In com- 
position it is a silicate chiefly of iron and magnesium. 

Enstatite resembles hypersthene in composition and properties, and 
its limited use in jewelry is to furnish " cat's-eyes " of a green color. The 
chatoyant effect is due usually to a fibrous structure. The principal 
locality for this variety is near Harzburg in the Harz. Schillerizing 
bronzite is found in a few localities in this country. 



169 



TURQUOIS 

This mineral differs from nearly all others held in favor as gems 

v)--'^"*' 1 

in not being transparent, and never-' occurring in the form of well- 
defined crystals. In composition turquois is a hydrous phosphate of 
aluminum, the percentages being: water, 20.6 per cent, alumina, 46.8 
per cent, and phosphorus oxide, 32.6 per cent. Thus, in composition 
as well as opacity, turquois differs from most other gems, they being 
usually silicates, or some form of silica. Besides the above ingredients 
turquois always contains a small percentage of copper oxide, and usually 
iron, calcium, and manganese oxides in small amount. It is the copper 
compound which undoubtedly gives turquois its inimitable color, that 
color to which it owes its chief charm as a gem. This color varies from 
sky-blue through bluish green, and apple-green to greenish gray. 

Of these colors, the pure sky-blue, or robin' s-egg blue, is by far 
the most highly prized, and is, in fact, the only standard color for the 
gem. Green is, however, the most common and the most lasting color 
of the mineral, and it is one of the faults of the gem that the blue 
shades often fade to green after being exposed to the light for a time. 
In a stone of first quality, however, especially a Persian turquois, such 
fading of color is exceptional. The hardness of turquois is 6. It is, therefore, 
somewhat more easily scratched than other gems. Its specific gravity 
varies from 2.6 to 2.8, being about that of quartz. It does not fuse 
before the blowpipe; but turns brown and assumes a glossy appear- 
ance. By the copper of the turquois the blowpipe flame is usually 
colored green. When heated in a closed glass tube the mineral turns 
brown, or black, and gives off water. Almost any of these tests will 
serve to distinguish true turquois from stones used to imitate it. It 
has a conchoidal fracture and waxy luster. On account of its opacity 
it is almost never cut with facets, but in a round, or oval form, with 
convex surface. The pieces desirable for cutting rarely reach a large 
size, so that big gems of turquois are comparatively unknown. 

Much of the so-called turquois used in former times was bone-turquois, 
or odontolite, made from fossil bone, colored by a phosphate of iron. It 
is still obtained mostly from the vicinity of the town of Simor, Lower 
Languedoc, France. It is sometimes known as Western, or Occidental 

170 ' 



turquois, in distinction from the Oriental turquois, most of which came 
originally from Persia. Odontolite does not retain its color by artificial 
light, as does true turquois, and may be further distinguished by giving 
off an offensive odor when heated, owing to decomposition of animal 
matter. Further, it is lighter than true turquois, and does not give 
a blue color, with ammonia, when dissolved in hydrochloric acid, as does 
true turquois. 

tx The finest turquoises have long come from Persia, from a locality 
not far from Nishapur, in the province of Khorassan. Here the min- 
eral occurs in narrow seams, in the brecciated portions of a porphyritic 
trachyte and the surrounding clay slate. There are several hundred 
mines in the region, and the entire population of the town of Maaden 
derives its livelihood from mining and cutting the stones. It is said 
that $40,000 worth of stones are taken from these mines annually. 
A pound of stones of the first quality sells at the mines for about 
$400, and is worth more than double that price in Europe. The mines 
must be very ancient. A description of them written in A. D. 1300 
is known ; and according to a tradition current in the region one of the 
mines, known as Isaac's mine, was opened by Isaac the son of Abra- 
ham. There are other turquois mines in Persia, but their product 
is comparatively small. Other Oriental localities from which gem 
turquoises are obtained are Sinai, in Arabia; the Kirgeshi Steppes, 
in Siberia; and the Kara-Tube Mountains, in Turkestan. Egypt also 
furnishes large quantities of turquois, which does not, as a rule, retain 
its color well. I/ 

Turquois is not an uncommon mineral in the United States, and 
many gems of fine quality have been obtained from mines within our 
borders. The oldest and best known mines are those at Los Cerrillos, 
New Mexico. This locality was long worked by Indians and Spaniards, 
as shown by the great extent of the excavations. There are pits to be 
seen here two hundred feet in depth, and piles showing that thousands 
of tons of rock have been broken out. Fragments of Aztec pottery, 
vases, cooking utensils, stone hammers, etc., are found at the mines, 
and trees of considerable size have grown over the once worked portions. 
Hence, the beginning of the mine workings must date back at least prior 
to the discovery of America. The mines were worked more or less 
by Spaniards in the early part of the seventeenth century with the 
consent of the Indians, or at least without hindrance from them. In 
1680, however, a large landslide occurred on the mountain at the 
mine, and many of the Indian miners were overwhelmed. Believing 
the Spaniards to be in some way responsible for the accident, and 

171 



perhaps fearing that their gods were displeased, the Indians rose in their 
might and expelled the Spaniards from the region. The Indians seem to 
have prized the turquois highly as an ornament, rudely polishing it, and 
using perforated pieces like the one shown in the accompanying colored 
plate for necklaces. They also decorated their idols and other objects 
of worship with pieces of turquois. The mountain at which the 
Los Cerrillos turquois mines occur is called Mount Chalchihuitl, in allu- 




Turquois mine 
Gem Turquois and Copper Co., Burro Mountain, near Silver City, New Mexico 

sion to an Indian name that is supposed to have been applied to tur- 
quois. The mountain is evidently of volcanic origin. The color of most 
of the turquois from this locality is apple -green rather than the 
highly prized blue, but some gems of a good blue have been obtained. 
Kunz, writing in 1890 of the sale of gems from this locality, says that 
the Indians usually dispose of them at the rate of twenty-five cents for 
the contents of a mouth, which is where they usually carry them. 
Several other localities in New Mexico are worked for turquois. In 
Cochise County, Arizona, is a locality known as Turquois Mountain, 
where considerable mining is carried on. ' Turquois is also mined in Gila 
County, Arizona ; Lincoln County, Nevada ; and San Bernardino County, 

172 



California. Several of these localities have been opened up recently, 
the present popularity of the gem perhaps having stimulated its output. 
Good New Mexico turquoises are quoted at $5 to $6 per carat at the 
present time. 

The much higher price commanded by turquois of a blue color has 
led to a counterfeiting of this color by staining green turquois or other 
stones with Prussian-blue. Kunz describes a method of detecting this 
stain which consists in washing the stone with alcohol ; and after wiping 
it, to remove any grease, laying it for a moment in a solution of am- 
monia, when the blue color, if artificial, will largely disappear. 

At how early a date turquois began to be prized as a gem is not known. 
The word turquois is a French word meaning Turkish, or a Turkish gem, 
and came to be applied because the gem was introduced into Europe 
by way of Turkey. It is probable that the gem has been in use from 
the remotest past among Oriental peoples, and it is certainly still highly 
prized by them. Not the least of the reasons for which it is held in 
high esteem by them, as well as by many Occidental individuals, is the 
good fortune it is supposed to bring to its possessor. One of the prov- 
erbs of the Orientals is, "A turquois given by a loving hand carries 
with it happiness and good fortune." That belief in the turquois as an 
agent of good luck was current in Shakespeare's time is shown by the 
grief which he represents Shylock as suffering over the loss of his 
turquois ring. Numerous other superstitions cling around the turquois. 
One of these, due probably to slight changes of color which the stone 
may undergo under certain climatic influences, is that if the owner of a 
turquois sickens it will grow pale, and at his death lose its color entirely ; 
but it will regain its color if placed on the finger of a new and healthy 
master. It was supposed to show the presence of poisons by sweating 
profusely. It is still used in the East as a remedy for dyspepsia, hernia, 
insanity, and cancerous sores Worn as an amulet, it is supposed to 
bring happiness, dispel fear, and render its wearer safe from drowning, 
lightning, and snake bite. In Egypt it is used to cure cataract if set in 
a silver ring, dipped in water, and applied to the eye with proper incan- 
tations. In Germany it is hi favor for engagement rings, owing to the 
belief that if either party prove inconstant the stone will make the 
fickleness known by weakening in color. It is curious that of the two 
non-crystallized gems, turquois and opal, one should be considered lucky 
and the other unlucky. Both are more liable to changes of color than 
other gems, and this fact has probably led to the ascription of good 
or ill fortune to them. 



173 



VARISCITE 

Variscite resembles turquois in many properties, being, like that min- 
eral, an opaque, hydrous phosphate of aluminum not occurring in 
distinct crystals. Its color is, however, normally an apple-green to emer- 
ald-green rather than blue, and its luster is more nearly vitreous than 
that of turquois. Its hardness is not equal to that of turquois, being 
but 4. Its specific gravity is 2.4. It is infusible before the blowpipe, 
but becomes white and colors the flame deep bluish-green on heating. 
The only form of it that has been used to any extent for gem purposes 
is one found in Cedar Valley, Tooele County, Utah. This is of a bright 
green color, and occurs as nodules in a crystalline limestone. Pieces of 
this give a pleasing effect when employed in jewelry in a manner similar 
to turquois. 



CALLAINITE 

This mineral has been found only in a Celtic grove at Mani-er-H'rock, 
near Lockmariaquer, in Brittany. It is there preserved in the form of 
rounded pieces in size between a flaxseed and a pigeon's egg, and was 
doubtless employed by the ancient Celts as an ornamental stone. Where 
they obtained it has never been learned. It is a hydrous phosphate of 
aluminum of a green color, spotted with whitish and bluish. Its hard- 
ness is 3.5 to 4 ; specific gravity 2.5. It is opaque to translucent. On 
account of its historic (or prehistoric) interest pieces have been cut and 
used to some extent in jewelry ; but its employment can obviously not 
be extensive on account of the small amount known. The name cal- 
lainite comes from callais, a precious stone mentioned by Pliny, the exact 
nature of which is not known, although it is generally supposed to have 
been turquois. 



174 




509 



Amazonstone, crystallized (Colorado). 

Labradorite, polished (Labrador). 

Suustone (Morway). 



FELDSPAR. 
Aniazonstone, crystallized (Colorado). 



Amazonstone (Colorado). 

Labradi trite, polished (Labrador). 

Moonstone, polished Norway). 



FELDSPAR 

Feldspar is the family name of several minerals closely related, and 
indeed grading into each other, but distinguished by mineralogists by 
separate specific terms. These minerals are all silicates of aluminum, 
with some alkali or alkali earth, having a hardness of about 6 and a 
specific gravity varying from 2.5 to 2.7. They are fusible with difficulty 
before the blowpipe, crystallize in the monoclinic or triclinic system, and 
cleave in two well-marked directions nearly or quite at right angles to 
each other. It is this latter property, probably, which led to the group- 
ing of these minerals as spar, since this term is applied in common lan- 
guage to any minerals which break with bright crystalline surfaces. The 
term field spar, of which feldspar is probably a corruption, was perhaps 
given the minerals of this group because of their widespread occurrence. 
The English spelling of the word is felspar. The feldspars form an essential 
part of nearly all eruptive rocks, and by their decomposition produce clays 
and other soils which may harden into great areas of sedimentary rocks. 
They are thus of great geological importance and interest. Usually the 
white crystals to be seen in an eruptive rock in contrast to the dark 
green or black of the pyroxene or hornblende, or the glassy, nearly 
colorless quartz, are feldspar. The feldspar may, however, contain more 
or less iron, and then take on a flesh color or become even darker. Feld- 
spar crystals can best be recognized by their prominent cleavage, which 
appears as numerous bright flat surfaces extending in any given crystal 
in the same direction. The crystals, while they may be of so minute 
dimensions as to be visible only with the microscope, may, on the other 
hand, reach in veins in coarse-grained granites a length of a foot or more. 

As ornamental stones only certain varieties of feldspar are valued, 
and their value depends on accidents of color or structure. The first of 
the feldspars which may be mentioned as being prized as an ornamental 
stone is amazonstone, or green feldspar. This in composition is what is 
called a potash feldspar, potash being the alkali which in combination 
with alumina and silica goes to make up the mineral. The percentages 
of each in a pure amazonstone are, silica 64.7, alumina 18.4, and potash 
16.9. The mineralogical name of the species is microcline, meaning 
small inclination, and refers to the fact that the angle between the two 

175 



cleavages of the mineral is not quite a right angle. The common color 
of microcline is white to pale yellow, but occasionally green and red occur. 

It is only to the green variety that the name of amazonstone is 
applied, a name meaning stone from the Amazon River. It first referred 
probably to jade, or some such green stone from that locality, and then 
came to include green feldspar. No occurrence of green feldspar in that 
region is now known. 

Practically all the amazonstone now used for ornamental purposes 
comes from three localities. These are the vicinity of Miask in the Ural 
Mountains, Pike's Peak, Colorado, and Amelia Court House, Virginia. 
In all these places the amazonstone occurs in coarse-grained granite, and 
is accompanied by quartz and mica. All gradations are found in color 
from the deep green to white, only the bright green being prized for 
ornamental purposes. The feldspar is usually well crystallized, and 
crystals of several pounds' weight may be found. A crystal will rarely 
be of a uniform color, streaks of paler green or white being commonly 
present. Only the uniformly colored portions are prized for ornamental 
purposes. The green often takes on a bluish tone, and blue sometimes 
even predominates. The color is doubtless due to some organic matter, 
as it disappears on heating, leaving the stone white. The stone is always 
opaque. Its use is not extensive, its sale being chiefly to tourists in 
the vicinity of the regions where it is found. Several other localities in 
the United States besides those mentioned afford the mineral, though not 
in large quantities. It occurs in two or three localities in North Caro- 
lina; in Paris, Maine ; Mount Desert, Maine; Rockport, Massachusetts ; 
and Delaware County, Pennsylvania. The finest comes from the Pike's 
Peak locality. Kunz states that when crystals from the latter locality 
were first exhibited at the Centennial Exposition in Philadelphia, in 
1876, they were a great surprise to Russian dealers, who had brought 
over some amazonstone from the Urals, expecting to sell it at what 
would now be considered fabulously high prices. 

The second species of feldspar which may be mentioned as of use as 
an ornamental stone is labradorite. This differs in composition from 
amazonstone in containing soda and lime in place of potash, the percent- 
ages in a typical labradorite being, silica 53.7, alumina 29.6, lime 11.8, 
and soda 4.8. Labradorite has the typical cleavage of feldspar and 
cleavage surfaces in the direction of easiest cleavage are usually marked 
by rows of parallel striae. These show that the mass is made up of a 
series of crystal twins in parallel position, and afford an excellent crite- 
rion for determining a triclinic feldspar. Labradorite is a common 
rock-forming mineral, especially in the older rocks. It is only, how- 

176 



ever, when it occurs in large pieces which exhibit a play of colors that ' 
it is prized as an ornamental stone. The labradorite exhibiting the latter 
property in the most remarkable degree and hence most valued is that 
found on the coast of Labrador near Nain, and the adjacent Island of 
St. Paul. It was first found here by a Moravian missionary named Wolfe, 
and brought to Europe in the year 1775. It occurs together with hy- 
persthene, in a coarse-grained granite, or perhaps a gneiss. From these 
it is weathered out by wave and atmospheric action, and occurs as beach 
pebbles. It is also mined from veins. Labradorite of pleasing color and 
opalescence occurs in a few localities in Canada, and in Essex County, New 
York. Two localities occur in Russia, one near St. Petersburg, and the other 
in the region of Kiew. The labradorite of the latter locality is the better, 
its occurrence being in a coarse-grained gabbro. The Labrador occur- 
rence exceeds all others, however, in abundance and beauty, and by far 
the larger quantity used in the arts comes from there. The play of 
colors which gives labradorite its attractiveness is rarely seen to advan- 
tage except upon a polished surface, but whether polished or unpolished, 
it only appears when the surface is held at a particular angle with refer- 
ence to the eye. Emerson thus describes it in his essay on " Experience," 
" A man is like a bit of Labrador spar, which has no luster as you turn it 
in your hand, until you come to a particular angle ; then it shows deep 
and beautiful colors." 

The play of colors seen in labradorite is not like that of the opal, 
which presents to the eye fragments of different colors varying in differ- 
ent positions, but appears as broad surfaces of a single color. It is only 
rarely that these colors change with a change of position. The colors 
over any given surface are not usually alike, but more than two or three 
tints are rare. Each tint is uniform where it occurs, but a tinted surface 
may be interspersed with many spots exhibiting no sheen. Both colored 
and uncolored portions have only vague outlines, and merge into each 
other at the edges. Bauer mentions a labradorite from Russia the col- 
ored portions of which formed a striking likeness of Louis XVI., the 
head being a beautiful blue against a gold-green background, while above 
appears a beautiful garnet-red crown. Excellent effects are sometimes 
produced in labradorite by cutting it in the form of cameos so as to 
make the base of different color from the figure in relief. Because of its 
chatoyancy labradorite is sometimes known as " ox-eye," or " ceil-de-bceuf." 
Of the different colors shown by labradorite blue and green are 
most common, yellow and red least so. These colors are regarded by 
Vogelsang as of different origin, the blue being, in his opinion, a polariza- 
tion phenomenon due to the lamellar structure of the feldspar, and the 

177 



yellows and reds the result of the reflection of light from minute 
included crystals of magnetite, hematite, and ilmenite. 

The gems known as moonstone and sunstone owe the play of colors 
which gives them their respective names to similar causes. These gems 
are generally some form of feldspar, although any mineral giving a 
similar sheen of color might be included under them. The moonstone 
of commerce comes chiefly fromkCeylon, where it occurs in large pieces 
the size of a fist in a clay resulting from the decomposition of a por- 
phyritic rock. Pieces of these when polished exhibit a beautiful pale 
blue light coming from within, which makes the stone prized as a gem. 
The cause of this light has usually been thought to be reflection from 
minute tabular crystals lying in parallel position in the stone. It seems 
to be partly caused also by absorption of red and yellow rays by the stone, 
leaving the violet and blue to be reflected and diffused. 

Moonstone varies from translucent to opaque, and from colorless to 
white, the essential feature being the blue opalescent light or chatoyancy 
exhibited from a polished surface. Good feldspar moonstones are worth 
from three to five dollars a carat. 

The Ceylon moonstone is sometimes known as Ceylon opal, but it 
is not opal. On the contrary, it is the variety of feldspar known as 
orthoclase, which is a potash feldspar, differing from the microcline 
just described in being monoclinic in crystallization and in having two 
cleavages meeting at right angles. Another species of feldspar used as 
, moonstone is albite. This is a soda feldspar, and is triclinic, but exhibits 
the chatoyancy characteristic of moonstone. One variety is known as 
peristerite, from the Greek word for pigeon, and is applied on account 
of the resemblance of the sheen to that of a pigeon's neck. It is found 
t^at Macomb, St. Lawrence County, New York. Albite found at Mineral 
Hill, Pennsylvania, also exhibits the chatoyancy of moonstone. Amelia 
Court House, Virginia, is another locality whence come pieces either of 
orthoclase or oligoclase exhibiting this property. Like most of the more 
or less opaque gems, moonstone is cut chiefly in the cabochon form. It 
is of late, however, cut in the form of balls, which are quite popular, the 
bringing of good luck being attributed to them. The brilliancy of moon- 
stone is considerably increased by mounting it against black. 

In the Middle Ages carrying a moonstone in the mouth was believed 
to be an aid to the memory. It was prescribed in cases of epilepsy, 
either as an amulet or powder. Belief in its efficacy for this purpose still 
persists among the Basques. During the period of increase of the moon 
it was regarded a potent love charm, while during the decrease of that 
luminary it was supposed to enable its wearer to foretell the future. 

178 



Sunstone is the term by which those kinds of feldspar are known 
which reflect a spangled yellow light. The appearance comes from minute 
crystals of iron oxide, hematite, or gothite, which are included in the 
stone, and which both reflect the light and give it a reddish color. Like 
labradorite the sheen is visible only when the stone is held at a certain 
angle. The sheen of sunstone is best visible when the stone is held in the 
sunlight or strong artificial light. The variety of feldspar to which the 
sunstone most in use at the present time belongs is oligoclase, a soda-lime 
triclinic feldspar. Like labradorite, it usually exhibits on the surface of 
easiest cleavage parallel striations, due to twinning structure. The best 
sunstone at the present time comes from Tvedestrand, in southern Norway, 
where it occurs in compact masses, together with white quartz, in veins 
in gneiss. Some also comes from Hittero, Norway. In Werchne Udinsk, 
Siberia, another occurrence was discovered in 1831. Previous to this 
Bauer states that all the sunstone known came from the Island of Sattel 
in the White Sea, and was very costly, although of a quality which would 
not now be deemed desirable. At the present time, although stones of 
fine quality can be obtained, sunstone is little used in jewelry, and its 
market value is very low. Statesville, North Carolina, and Delaware 
County, Pennsylvania, are two localities in the United States where good 
sunstone has been obtained. 

Both sunstone and moonstone can be accurately imitated in glass, 
and the distinction of the artificial from the real by ocular examination 
alone might be somewhat difficult. Glass, however, lacks the cleavage 
of feldspar, and is somewhat heavier and softer. The discovery of the 
method of making artificial sunstone is said to have been accidental, and 
was made at'Murano, near Venice, when a quantity of brass filings by 
chance fell into a pot of melted glass. The product was for a long time, 
and is still, used in the arts under the name of goldstone. Sunstone is 
sometimes known as aventurine feldspar, in distinction from aventurine 
quartz, which presents a similar appearance, owing' to the inclusion of 
scales of mica. The term aventurine is from the Italianxziwmwra, 
meaning chance, and refers to the chance discovery above referred to. 
Other forms of feldspar than those here described occasionally furnish 
gems which are transparent and colorless, and valued for their luster. 
The varieties chiefly employed in this manner, are adularia, a variety of 
orthoclase which is often transparent, the best specimens being obtained 
in Switzerland, and oligoclase, in the transparent form in which it is 
found near Bakersville, North Carolina. 



179 



OBSIDIAN 

This is a natural glass which is used to some extent at the present 
day for ornamental purposes. In earlier times, especially among the 
prehistoric peoples of the western hemisphere, its use was very exten- 
sive, both for utensils and ornamental articles. 

Obsidian is a product of volcanic outflows, being produced where 
a rapid cooling of certain liquid lavas has taken place. In color it 
may be black, gray, green, red, brown, or yellow, and in diaphaneity 
may vary from transparent to opaque. The kind used almost exclu- 
sively in the arts is of black color, generally transparent only in thin 
pieces. 

The properties of obsidian differ little from those of manufactured 
glass. Its hardness is 5-5^; specific gravity 2.3-2.5. It has a vitreous 
luster, and is brittle, breaking with a large conchoidal fracture which 
is quite noticeable. Its extreme brittleness makes cutting of it difficult. 
It fuses rather easily before the blowpipe to a porous, gray mass. 
Being amorphous it cannot be distinguished optically from glass, like 
which it is singly refracting. It frequently contains partially crystal- 
lized inclusions, however, and gas pores, which are not common to arti- 
ficial glass. When these ,are arranged in regular order the obsidian 
shows a chatoyancy, or schillerization, which gives a pleasing effect. 
In chemical composition obsidian shows a higher percentage of alumina 
and a lower one of alkalies than artificial glass. The following is the 
composition of an obsidian from the Lipari Islands: Silica, 74.05, 
alumina, 12.97, iron oxide, 2.73, lime, 0.12, magnesia, 0.28, potash, 
5.11, soda, 3.88, loss on ignition, 0.22. Obsidian is not easily attacked 
by acids. One of the largest known deposits of obsidian in this coun- 
try occurs in the Yellowstone Park, Wyoming. The locality is known 
as Obsidian Cliff, and the deposit has a thickness, according to Profes- 
sor Iddings, of 75 to 100 feet. There are evidences that the Indians 
obtained obsidian here for use in their arts, as flaked fragments are 
found in the vicinity. The color of this obsidian is for the most part 
black, but shades of red and yellow occur. 

A variety of obsidian, showing red and black in alternate streaks, 
or spots, occurs here as well as in other localities. This is known as 

180 



marekanite, or " mountain mahogany," and makes a pretty stone, which 
is used for the manufacture of some objects. 

The mines from which the Aztecs and their successors seem to have 
obtained the greater part of their obsidian are located in the State 
of Hidalgo, Mexico, about thirty miles east of Pachuca. The locality 
is known as the Sierra de las Navajas, or Hill of the Knives. Here 
hundreds of acres have been worked over, and heaps and ridges of obsidian 
fragments are continuous for one or two miles. The mining seems to have 




Obsidian cliff, Yellowstone Park 

been performed by digging pits from 6 to 20 feet in depth. Large pieces 
of obsidian were thus obtained, which were shaped into so-called cores, 
cylindrical pieces of varying diameters. From these, articles of the 
desired shape were obtained by flaking and polishing. Immense heaps 
of flakes show that working of the obsidian was carried on here for 
centuries. Articles made from it are found among the Aztec ruins in 
Mexico, and as far north as the mounds of Ohio. They are of great 
variety, and many of them exhibit much skill in workmanship. They 
include masks, ear ornaments, lip ornaments, spear heads, arrow heads, 
knives, and razors. Mirrors were also made from the obsidian. To this 
latter use obsidian was put by the Romans in the time of Pliny. They 

181 



also manufactured ring stones, seals, and other ornaments from it. The 
source of their obsidian was probably the island of Lipari, for exten- 
sive fields of beautiful obsidian are still known and worked there. 
It also occurs in the neighboring islands. 

Its use at the present time is chiefly for making mourning jewelry 
it being preferred by some to jet. Obviously, it can be closely imitated 
in glass; and though the cost of cut obsidian is small, glass is still 
cheaper. The schillerizing, or chatoyant obsidian, is more highly prized 
than the plain, and cut en cabochon it makes a very pretty ring stone. 
Obsidian is sometimes called Iceland agate, perhaps because obtained 
in Iceland, although by some it is thought that the name is a corrup- 
tion of island agate, from the occurrence of the stone in the islands 
of the Mediterranean. 



182 



OF THE 

( UNIVERSITY j 

or 











590 



ChlorastroHte, polished (Isle Royale). 
Hematite, polished (England). 

Thoiusouite, polished (Lake Superior). 



MINOR GEMS. 
Cat's-eye, Quartz, polished (Ceylon). 



Variscite, polished (Utah). 

Moldavite, cut (Bohemia). 
Thomsonite, rough (Lake Superior). 



MOLDAVITE 



This term is applied to a transparent green stone found occurring 
in small pieces in Bohemia, in the region drained by the river Moldau, 
whence the name moldavite. The color of the stone is of the peculiar 
character generally designated as bottle-green; and since its physical 
characters, such as hardness, fracture, optical qualities, etc., also resemble 
those of glass, the view was long held that the fragments found were 
remains from some long since demolished glass works. Latterly, however, 





Moldavite pebbles as found 



Dr. Franz Suess has advanced the opinion that the fragments are of extra- 
terrestrial origin, and represent a peculiar kind of meteorite. These 
views he has set forth in an elaborate work upon the subject. 

Proof of such an origin of moldavite would lend an added interest 
to it, and probably increase its use for jewelry, the present employ- 
ment of it being rather limited. The pieces as found are waterworn 
pebbles of various shapes, usually with deeply indented or pitted sur- 
faces, as shown in the accompanying cut. In size they are never 
larger than one's fist, while they are usually much smaller. They are 
found in the beds of brooks and in the soil. Regions near Budweis 
and Trebitsch are especially prolific in the pebbles. Moldavite has a 
hardness not quite equal to that of feldspar, being a little less than 6. 

183 



It is thus somewhat harder than ordinary glass. Its specific gravity 
ranges from 2.32 to 2.36. Unlike ordinary glass and obsidian it is 
almost infusible before the blowpipe, and when fused remains perfectly 
clear on cooling. It differs considerably in chemical composition from 
ordinary glass, having as it does a higher percentage of silica, consider- 
able alumina, and a small percentage of alkalies. The percentages of silica 
range between 88 per cent and 78 per cent ; those of alumina between 5 
per cent and 13 per cent ; and those of potash and soda between 1 per 
and 2.5 per cent. The following is an analysis of a dark green moldavite 
from Budweis: Silica, 77.75, alumina, 12.90, iron protoxide, 2.60, lime, 
3.05, magnesia, 0.22, potash, 2.58, soda, 0.26, water, 0.10. In ordinary 
glass the percentage of silica is not much above 50 per cent ; there is 
almost no alumina, while lime and magnesia amount to about 20 per 
cent, and potash and soda 20 per cent to 25 per cent. 

Glassy pebbles similar to moldavite are found on the island of Billiton, 
near Java. These are known as billitonite. They are also found in 
Borneo and several parts of Australia. In these places they are believed 
to be of volcanic origin if not meteoric. 

Of these different occurrences of moldavite only the Bohemian is so 
far used to any extent in jewelry. Owing to the abundance of the mate- 
rial the stones cut from it are not expensive, being valued at no more 
than quartz or agate. Actual glass can easily be substituted for it 
with little chance of detection. 



184 



APATITE 

This common and widely distributed mineral occasionally affords 
transparent crystals which admit of limited use in jewelry. The cut 
stones cannot, however, endure much wear, as the hardness of the 
mineral is only 5. The colors which the crystals may present are 
violet, light blue, yellow, rose, and various shades of green. One color 
and degree of transparency may characterize an entire crystal, or but 
a portion of one. The crystals have nearly always the shape of a simple 
hexagonal prism, the mineral crystallizing in the hexagonal system. 
In composition apatite is phosphate of lime, with a small percentage 
of fluorine or chlorine. It is, therefore, much like bone in constitu- 
tion. It is barely fusible before the blowpipe. On moistening a frag- 
ment with sulphuric acid, and heating, the flame is colored pale green 
from the phosphorus present. Apatite is attacked and dissolved by 
strong acids. Its specific gravity is 3.17-3.23. Its luster is vitreous 
to subresinous. 

The best known transparent apatite is obtained at Ehrenfriedersdorf, 
in Saxony. Here transparent crystals of a violet color occur capable 
of affording cut stones of a few carats in weight. From Arendal, 
Norway, greenish-blue crystals are obtained, furnishing the variety known 
as moroxite. A yellowish - green variety, known as asparagus stone, 
comes from Murcia, Spain. At Mount Apatite, Auburn, Maine, crystals 
of pink, green, and violet colors have been obtained which sufficiently 
resembled tourmaline to be mistaken for it. 

Apatite occurs most commonly in metamorphic crystalline rocks, 
especially limestone. It is also found in granites and mica schists, 
and in sedimentary rocks ; but in the latter it is usually an amorphous 
mineral. 



185 



FLUORITE, OR FLUORSPAR 




Few if any minerals exceed this in beauty and variety of colors. In 
transparency and luster also it leaves little to be desired. Yet its soft- 
ness and brittleness are such that it can have but a limited use for gem 
purposes. In color it imitates closely many of the well-known gems, and 
cut fluorites are often designated as "false" emerald, ruby, amethyst, 
topaz, etc. From genuine stones of these names fluorite can readily be dis- 
tinguished by its relative softness. Its hardness is 4 in the scale, and it is 
therefore readily scratched by a knife-blade or a piece of glass. Fluorite 

crystallizes in the isometric 
system, and has an eminent 
cleavage parallel to the faces 
of the octahedron. This cleav- 
age is so strongly developed 
that it is difficult in cutting 
the mineral to prevent cracks 
starting and portions breaking 
off. The cleavage also pro- 
duces flaws in the stones. 
Crystals of fluorite generally have the form of simple cubes. These 
cubes are sometimes modified by other forms, and twinned cubes are 
not uncommon. One of the most unique and pleasing properties of 
fluorite is that known as fluorescence. When pieces of the mineral are 
heated gently their interiors light up with a bright glow, usually colored, 
and this color is quite independent of that of the mineral a blue fluorite, 
for instance, often exhibiting an emerald-green fluorescence, a green 
stone, a purple, and so on. Sometimes the heat of the hand, or the 
striking of two pieces together, is sufficient to excite this glow, and an 
increase of heat may cause it to change color. If heated too highly or 
too long the mineral loses both this property and its inherent color. The 
cause both of the color and the fluorescence is undoubtedly hydrocarbons 
which exist in the mineral. 

Fluorite is a simple fluoride of calcium, having the percentage com- 
position fluorine 48.9, and calcium 51.1. It fuses rather easily before 
the blowpipe to a white enamel, which gives an alkaline reaction. Its 

186 



Crystal forms of fluorite 



specific gravity ranges from 3 to 3.25. Besides the transparent crystal- 
lized forms, it is found in fibrous and granular masses. It is a common 
mineral, and widely distributed. Its most common occurrence is in veins 
accompanying ores of lead, silver, etc. It also forms beds. The locali- 
ties affording the best known, and in many respects the finest, fluorite 
are Cumberland and Derbyshire, England. In these localities the fluorite 
is known by the name of Blue John, or Derbyshire spar, and is worked 
to some extent into large ornamental objects, such as table-tops, vases, 
etc. These articles are turned on lathes, the stone being first soaked in 
gum-water, or similar adhesive, to prevent its falling apart. One of the 
finest pieces of this sort of work ever executed is to be seen in the 
Museum of Practical Geology, London. This object is a vase 2 feet 
8 inches high, and 3 feet 7 inches in its greatest circumference. It was 
made by Mr. Vallance, of Matlock, from several pieces of fluorite occur- 
ring near Castleton, in Derbyshire. 

The mining district of Saxony affords large quantities of fluorite. 
Red is one of the rarest colors exhibited by this mineral, and red fluorite 
comes almost exclusively from the St. Gothard, Switzerland. 

In our own country many deposits of fluorite occur, though little use 
is made of them for ornamental purposes. ^-Macomb, New York, has 
furnished a large quantity of green crystals, exceeding in size and equal- 
ing in color any ever found. An extensive deposit of fluorite in Illinois 
is mined for use as a flux, but the crystals are rarely clear enough for 
ornamental use. 



187 



Hematite is an oxide of iron occurring in nature which takes on a 
variety of forms and shades, but is used in jewelry only when compact 
and of an iron-black color. In this form it is used especially for in- 
taglios, but also for carving into ornaments of various sorts. Its hardness 
is 6, and specific gravity 4.9-5.3. Its composition is, iron 70 per cent, 
and oxygen 30 per cent. While in a mass it is invariably opaque, and 
often black in color ; in a thin splinter it may be seen to be slightly trans- 
lucent and red. This red color always characterizes the powder or streak 
f hematite, and is one of the surest means of identifying the mineral. 
'As the color resembles that of blood, the Greeks believed the mineral to 
be concreted blood, and the name hematite is from their word for that 
substance. Under the name of bloodstone it was long believed to be a 
curative of hemorrhages, and Robert Boyle, the eminent physicist, writing 
as late as 1672, gravely relates a cure of a case of nasal hemorrhage of 
long standing through wearing a bloodstone about the size of a hen's 
egg about the neck. 

Powdered hematite forms the rouge of commerce used so extensively 
for polishing. 

Hematite was used in the carved form by the ancients as well as the 
moderns, a number of cut pieces having been found in the ruins of Baby- 
lon. Intaglios of it have also come down to us from the Romans. Large 
polished surfaces of hematite make excellent. mirrors, and frequent use was 
made of it for this purpose in earlier times. Hematite is so abundant 
over the earth's surface that it has little intrinsic value except as an ore 
of iron. That used in jewelry comes largely from northern Spain. Hem- 
atite of a similar character is obtained in the Island of Elba, Cumberland, 
England, and in the Lake Superior region of our own country. Besides 
its use for seals, it is employed to make imitation black pearls. Certain 
fibrous occurrences of hematite when cut in rounded forms give a star- 
like appearance similar to that exhibited by star sapphires. 



188 



PYRITE 

Pyrite, also known as marcasite by jewelers, is a brass-yellow min- 
eral with metallic luster, employed to some extent for purposes of orna- 
ment. It is widely distributed in the earth's crust, and from its yellow 
color and metallic luster is often mistaken for gold. A common name 
for it, therefore, is " fool's gold." In composition it is a sulphide of iron, 
the percentages being, sulphur 53.4 and iron 46.6. Its hardness is a little 
below that of quartz, or 6^. The name pyrite is from the Greek word 







Crystal forms of pyrite 

for fire, and was given in allusion to the fact that owing to its hard- 
ness it will strike fire with steel. It is heavy, its specific gravity being 
five times that of water. It is quite brittle. It crystallizes in the iso- 
metric system, crystals of cubic or cuboidal forms being the most com- 
mon. Owing to its abundance in nature it has practically 110 intrinsic 
value except in large quantities, in which case it forms an ore of sulphur. 
When cut into various objects of ornament, however, it has quite a 
pleasing effect, and at times has been much in favor. It is used for 
ornamenting bracelets, brooches, scarf-pins, and the like, and in certain 
forms in rings. 

For these purposes it has usually been artificially facetted, thus dis- 
playing its brilliant luster. An American firm has recently, however, 
employed the pyrite found in the form of a coating of small, bright 
crystals, nearly uniform in height, for use in jewelry. These coatings 
are obtained from beds of anthracite coal, and only require smoothing 
on the back and cutting into pieces of suitable size and shape to be 
made available. 

One of the drawbacks to the use of pyrite in this way is its easy 
liability to tarnish, and the difficulty afterwards of restoring the original 
luster. Some groups of crystals will remain bright a long time while 

189 



others tarnish rapidly. This is especially true of marcasite, the ortho- 
rhombic form of iron sulphide, which is sometimes confounded with 
pyrite. This even decomposes and crumbles away in time. 

Pyrite was used to quite an extent in earlier times for mirrors, 
large pieces of it being ground and polished until they gave a good 
polish. Among the remains of the Incas of Peru have been found 
large numbers of these pyrite mirrors. 



190 



CHLORASTROLITE 

f This mineral, the name of which means " green-star stone," is solely 
of American occurrence, and thus far has been found at but a single 
locality. It occurs at Isle Royale, an island in Lake Superior, in the 
form of beach pebbles. These pebbles come from the adjoining amygda- 
loidal trap rock, out of which they weather. They are opaque, and 
of light, bluish-green color, with a mottled effect arising from a stel- 
lated or radiated structure. This structure, when the stone is polished, 
affords a chatoyancy which is very pleasing. It is especially desirable 
in a good stone that the radiation should emanate from the center, 
in which case a cat's-eye effect is obtained. The pebbles which make 
good stones are mostly small; but some an inch in diameter are 
known. The hardness of the mineral is 5.5, and its specific gravity 
3.18. It is not a homogeneous mineral but a mixture, composed 
chiefly of a hydrous aluminum silicate. The stones have not attained 
extensive use as yet, except as they are sold in quantities to tourists in 
the Lake Superior region, i/ 



191 



THOMSONITE 

(MESOLITE.) 

6/iAn occurrence of this mineral, which is used ornamentally to some 
extent, is obtained, like chlorastrolite, in the form of waterworn pebbles 
weathered out of an amygdaloidal trap. The pebbles are found on 
the shores of Lake Superior, near Grand Marais. They are opaque, 
and exhibit concentric structure in layers of various shades of color> 
such as olive-green, flesh-red, cream, and white. There are often 
several centers of structure in a single pebble, giving a unique and 
pleasing effect. The pebbles range up to an inch in diameter, and 
in cutting are simply rounded so as to best bring out the various 
colors and centers of structure. The hardness of the mineral is 5; 
specific gravity 2.2-2.4. Its luster is vitreous to pearly. Its compo- 
sition is that of a hydrous silicate of aluminum, sodium and calcium, 
and its occurrence is almost wholly as a secondary mineral filling the 
cavities of igneous rocks. 

The mineral at Grand Marais has long been known as thomsonite, 
and is generally sold under that name; but Professor N. H.Winchell 
affirms that it is in reality the allied mineral mesolite. ( i/ 



192 



PREHNITE 

This mineral affords a semi-transparent stone, which, when of a deep 
oil-green color, may have a limited use in jewelry. It does not often occur 
in nature in the form of large distinct crystals, but usually as aggre- 
gates of minute crystals, in firm incrusting masses, with a radiated 
structure. Portions of these masses, when of a uniform color, form, 
when cut en cabochon, pleasing stones. 

In composition prehnite is a hydrous silicate of aluminum and cal- 
cium, having the percentages : silica 43.7, alumina 24.8. It is easily 
fusible before the blowpipe and is attacked by acids. Its hardness 
is 6.65; specific gravity 2.80-2.95; its luster is vitreous. Its occur- 
rence is almost wholly in connection with basic eruptive rocks, in the 
veins and cavities of which it forms a secondary mineral. 

Some of the most richly colored prehnite known is obtained at Pater- 
son and Bergen Hill, New Jersey. In the Lake Superior region prehnite 
accompanies native copper, and affords a stone which is considered 
worthy of cutting. Many localities in the Alps furnish prehnite, and 
handsome pieces are obtained by polishing masses occurring in'^China. 
Some prehnite comes from the Cape of Good Hope, and when cut 
is known as "Cape chrysolite." 



193 



RHODONITE 

Rhodonite is a silicate of manganese, of a pink, or flesh-red color. 
It does not furnish transparent gems, but occurring massive in large 
pieces affords material for table-tops, vases, jewel-boxes, paper-weights, 
and other large objects in which such a color is desired. The stone 
has a slight translucency, which heightens its effect when polished, 
and it is also like jade in being quite tough. The Russians use it more 
extensively perhaps than any other people, often introducing it into 
ornamental and decorative works, and it is a stone especially prized 
by the Imperial family. The hardness of rhodonite is 5.5-6.5 ; its spe- 
cific gravity 3.4-3.7. Before the blowpipe it fuses easily and becomes 
black. It crystallizes in the triclinic system. Its chemical composition 
when pure is, silica 45.9, manganese protoxide 54.1. Rhodonite occurs 
in a number of localities, the district of Ekaterinburg, in the Urals, 
affording that used by the Russians. Here it occurs in a massive, 
marble-like form. At^Cummington, Massachusetts, according to Kunz, 
large quantities of a pink and red color occur which have been used 
for ornamental objects. A feature of this rhodonite is its being mottled 
and streaked with black, which causes it to blend prettily with silver. 
Rhodonite of the variety of fowlerite, that is, containing zinc, occurs 
among other zinc ores at Franklin, New Jersey. It is sometimes used 
for ornamental purposes. 



194 






598 



Satin Spar, polished (Italy). 

Thulite, polished (Norway). 

Serpentine, polished (Cornwall, England). 



ORNAMENTAL, STONES. 

Smithsoiiite, polished (Greece). 
Serpentine, polished Cornwall, England). 
Serpentine, polished (Cornwall, England;. 



ZOISITE 

Another rose-red massive stone is furnished by the variety of zoisite 
known as thulite. This resembles rhodonite in color somewhat, but 
is easily distinguished by its chemical characters, zoisite being a hydrous 
silicate of calcium and aluminum. It is somewhat harder than rhodo- 
nite, its hardness being 6-6.5. The name thulite is from Thule, 
an ancient town of Norway, and the occurrence of thulite is confined 
almost exclusively to that country. Its use for ornamental purposes 
is very limited; but it answers well where objects of its particular 
color are desired. 



PRECIOUS SERPENTINE 

This mineral resembles jade in appearance and properties, and is 
suited to many of the ornamental uses to which the former is put. 
Not a little so-called jade is doubtless serpentine. The hardness of 
serpentine is somewhat below that of jade, it being 5.5, and lower. It 
is also lighter, its specific gravity being 2.50-2.65. The blowpipe and 
chemical characters also distinguish it, serpentine being practically 
infusible before the blowpipe, and decomposed by acids, while jade is 
more or less fusible, and not attacked by acids. In composition serpen- 
tine is a hydrous magnesium silicate having the percentages, silica 44.1, 
magnesia 43.0, and water 12.9. Like jade it does not crystallize, but 
occurs in massive forms, which show crystalline structure. One of the 
most pleasing properties of serpentine is its luster, which is subresinous 
to oily. This, coupled with translucency which characterizes most pre- 
cious serpentine, and the excellent polish which it takes, make the stone 
of rich effect. 

The color of precious serpentine is primarily some shade of green, vary- 
ing from yellowish-green to blackish-green. This color may be uniform 
or mottled, or may include spots of other minerals, such as the white of 
calcite, as in several of the serpentine marbles, or cherry-red from iron 
oxide, as in the serpentine of Lizard, England. The name serpentine 
alludes to the green, serpent-like cloudings best seen in serpentine marble. 

195 



Precious serpentine is obtained in many parts of the world, among 
the localities being Afghanistan (which furnishes an almost transparent 
variety in large masses), the Island of Corsica, Fahlun and Gulso in 
Sweden, the Isle of Man, and the Lizard, Cornwall, England. 

In the United States a rich green variety of serpentine, known as 
williamsite, is found in Texas, Lancaster County, Pennsylvania, and is 
cut into various charms and ornaments. It varies in color from dark 
green to light apple-green. A golden to greenish - yellow serpentine 
occurs at Montville, New Jersey, which would admit of use for the 
manufacture of small objects, such as dishes and charms. 

A variety of serpentine known as bowenite is found near Smithfield, 
Rhode Island, varying in color from pure white to deep green. 

<A dark green serpentine occurs at Santa Catalina Island, California, 
which is of sufficient homogeneity to be turned into dishes of various 
shapes, some being seven or eight inches in diameter. 

Serpentine marble, which usually consists of a mixture of serpentine 
and calcite, forms quite extensive deposits at several localities in the 
country, among which may be mentioned Moriah, New York ; Dublin, 
Harford County, Maryland ; National City, California ; and Valley, 
Washington. This is used like marble as slabs for table-tops and wall 
decorations. 

Coarse, common serpentine forms extensive rock masses, and moun- 
tains of it exist ; but the use of the mineral for ornamental purposes is 
confined to pieces of pleasing color, homogeneity, and translucency. 



196 



MALACHITE 

Malachite is a green carbonate of copper containing water, the per- 
centages being in the typical mineral: cupric oxide 71.9, carbon dioxide 
19.9, and water 8.2. It is the common form which copper assumes 
when it, or even its ores, oxidize in the air. Many of the green stains 
on rocks, or minerals, can be correctly referred to malachite. It is only 
valued for ornamental purposes, however, when it occurs in compact 
masses, usually exhibiting concentric layers. Malachite in this form 
takes a fine polish. Malachite is not a hard mineral, its hardness being 
between 3.5 and 4. It can, therefore, be scratched with a knife. It 
is comparatively heavy, weighing four times as much as an equal 
bulk of water. When heated before the blowpipe it fuses easily, 
coloring the flame green. By heating long enough on charcoal it can 
be made to yield a globule of copper. It is easily attacked by com- 
mon acids, causing effervescence of carbon dioxide. This test can 
be used to distinguish it from the silicate of copper, chryscolla, which 
has the same color. 

Besides its occurrence in massive forms, as noted above, malachite 
not uncommonly is found in tufts and rosettes incrusting other min- 
erals. This is an especially common occurrence in mines in Arizona, 
and affords specimens of great beauty, especially when the green tufts 
of malachite are seen upon brown limonite, for then the appearance 
of moss on wood is closely simulated. Such material is, of course, 
too fragile to be used for decorative purposes. 

Malachite is prepared for ornamental use by sawing masses of the 
character of those previously referred to into thin strips, which are 
then fastened as a veneer on vessels of copper, slate, or other stone 
previously turned to the desired shape. Putting pieces together so that 
neither by their outlines nor color will it appear that they are patch- 
work, requires a high degree of skill, and such work is done almost 
exclusively in Russia. Table tops, vases, and various other vessels are 
manufactured in this way, and form objects of great beauty. The pillars 
of the Church of Isaac, in St. Petersburg, are of malachite prepared in 
this way, and there are similar pillars in the Church of St. Sophia, Con- 
stantinople, said to have been taken from the Temple of Diana at Ephesus. 

197 



Occasionally the desired object can be turned from a single piece 
of malachite; but pieces of sufficient size for this purpose are rare. 
Bauer describes one piece found in the Gumeschewsk mines which was 
17^ feet long, 8 feet broad, and 3^ feet high, and compact throughout. 
This is probably the largest single mass known. 

Russia furnishes most of the malachite suitable for work of this 
kind, and the art of cutting and fitting the stone is possessed almost 
exclusively in that country. Most of the Russian malachite has been 
obtained from the mines of Nizhni-Tagilsk and Bogoslowsk, in the 
northern Urals, or Gumeschewsk, in the southern. The supply has 
gradually decreased till now only the Nizhni-Tagilsk mines are pro- 
ductive. The malachite occurs there in veins in limestone. 

Besides the Urals, fine malachite, suitable for cutting, comes from 
Australia. Burra Burra, in New South Wales, and Peak Downs, in 
Queensland, are localities whence good Australian malachite is obtained. 

Malachite, as a mineral, is common in copper mines in the United 
States; but it is only in Arizona that it is found of a quality suitable 
for cutting. A variety from Morenci, Arizona, consists of malachite 
and azurite, and gives a combination of green and blue that is unique 
and pleasing. Less use has been made of such material for ornamental 
purposes than might have been, for most of it has unfortunately been 
smelted as a copper ore. 

Malachite is rarely used for rings, or small jewels, being cut most 
extensively into earrings, bracelets, inkstands, and similar objects. Art 
objects of malachite seem to have been in much favor with Russian em- 
perors as gifts to contemporaneous sovereigns, and so bestowed are to be 
seen in numerous palaces in Europe. Perhaps the most famous of these 
gifts is the set of center-tables, mantelpieces, ewers, basins, and vases 
presented by the Emperor Alexander to Napoleon, and still to be seen 
in an apartment of the Grand Trianon at Versailles. 

Malachite was well known to the ancients, and like other precious 
stones was worn as an amulet. It was called pseudo - emerald by 
Theophrastus. Its name is from the Greek malake, the word for 
mallows, and was given doubtless on account of its green color. 

It was regarded in the sixteenth century as a powerful anaesthetic, 
being used internally or, applied to the injured parts. It was also used 
as a purgative and to increase the strength and growth of children. The 
Chinese still ascribe magical properties to vases made from it. 

Azurite, the blue mineral which often accompanies malachite, is like- 
wise a hydrous carbonate of copper, and occasionally occurs so that it 
can be used with malachite for ornamental purposes. 

198 



CHRYSOCOLLA 

This mineral in its pure state is too soft to be used as a gem, 
but mixed with quartz, or constituting practically a stain, it affords 
blue and green stones, resembling turquois on the one hand and chryso- 
prase on the other. In fact, it is not unlikely that some of the so-called 
turquois obtained in Utah and Nevada is in reality chrysocolla. Typically 
chrysocolla is a hydrous silicate of copper, having the percentages : silica, 
34.3, copper oxide, 45.2, and water, 20.5. It thus resembles dioptase 
in composition, but unlike that mineral it does not crystallize. Its 
hardness varies from 2 to that of quartz if mixed with that mineral. 
Its specific gravity is slightly greater than that of quartz. Its blowpipe 
reactions do not differ from those of turquois essentially, because of the 
content of copper in the latter, but chrysocolla gives no test for phos- 
phoric acid. 

When of good color and hardness chrysocolla affords a stone resem- 
bling turquois or chrysoprase. 

Chrysocolla occurring in Nizhni-Tagilsk, in the Urals, is of a sky- 
blue color, and is known as demidovite. It has been cut to some extent. 
In our own country chrysocolla occurs in numerous copper mines, espe- 
cially in Michigan, Arizona, and Nevada, but not much use has yet been 
made of it in jewelry. 

The name chrysocolla is from the Greek, and means gold glue. It 
was so called from its resemblance to a substance used by the ancients 
for soldering gold. It is mentioned by Pliny, and was probably known 
to the Romans, though not used for ornamental purposes. 



199 



DIOPTASB 

The name of " copper emerald," by which this mineral is sometimes 
known, well indicates both its composition and appearance. No other 
mineral so closely imitates the emerald in color, although it differs in 
being slightly darker and less transparent. It possesses also a distinct 
rhombohedral cleavage, so prominent as to give the mineral its name, 
from two Greek words dia, through, and optomai, to see, because the 
cleavage can be seen on looking into a crystal. Dioptase is a hydrous 
silicate of copper, having the percentage composition: silica 38.2, cupric 
oxide 50.4, water 11.4. It crystallizes in the rhombohedral division 
of the hexagonal system, forming short prismatic crystals resembling 
superficially an isometric dodecahedron. Its chemical characters suffi- 
ciently distinguish it from emerald, as it gives before the blowpipe the 
green flame of copper, and gelatinizes with hydrochloric acid. Its chief 
defect as a gem consists in its lack of hardness, which is only 5. It is 
therefore rather easily scratched. Its specific gravity is somewhat high, 
3.28-3.35. It has vitreous luster, and is brittle. 

The best dioptase comes from the Kirghese Steppes of Siberia, where 
it occurs on the hill Altyn Tube, occupying seams in a compact lime- 
stone. The crystals here are so perfect that they can be worn uncut. 
Small crystals and rolled pieces are found in auriferous sands in various 
places in the Jeniseian Government in Russia, and fine crystals are 
reported from the Mindouli mine in the French Congo State. It has 
also been obtained at the copper mines of Clifton, Arizona, but the 
crystals are small, and of little value for gem purposes. 



200 



LAPIS LAZULI 

This stone was the sapphire of the Greeks, Romans, and Hebrew 
Scriptures. Pliny likened it to the blue sky adorned with stars. Large 
quantities of worked pieces of it are found in early Egyptian tombs, 
and the Chinese have long held it in high esteem. Marco Polo visited 
Asiatic mines of the mineral in 1271 A. D., and these had doubtless 
been worked for a long time previous. Besides its value as a stone, it 
was in former times used as a blue pigment, giving the ultramarine-blue. 
In modern times not only has the esteem in which the stone is held for 
ornamental purposes declined, but the mineral can be artificially made 
so as to give the desired blue color for paints, and thus the use of the 
natural lapis lazuli has greatly diminished. It is still, however, carved 
to make vases, small dishes, brooches, and ring stones, and is used to a 
considerable extent for mosaic work. When, also, pieces of sufficient 
size and of a uniform color can be found, large carved objects may be 
made which command a high price. 

The stone known as lapis lazuli as it occurs in nature is not a single 
mineral but a mixture of several, among which are calcite, pyrite, and 
pyroxene. From these, however, it is possible to separate a mineral of 
uniform composition sometimes crystallized in dodecahedrons, which is 
probably the essential ingredient of the stone. This mineral is known 
as lazulite, and in composition is a silicate of soda and alumina, with a 
small quantity of sodium sulphide. It is by making a substance of this 
composition that the artificial ultramarine is produced. The artificial is 
said to be as good as the natural for a pigment, and can be produced for 
a three-hundredth part of the cost. The natural lapis lazuli has a hard- 
ness of 5^ and a specific gravity about like that of quartz. It is quite 
opaque. In color it is blue, varying from the prized ultramarine to paler, 
and at times is of a greenish shade. It is said the pale colored portions 
can be turned darker by heating to a red heat. When the variety from 
Chile is heated in the dark it emits a phosphorescent green light. The 
stone in nature is often flecked with white calcite. Portions so affected 
are not considered as valuable as the uniform blue. Grains of pyrite 
are also usually scattered through the stone, giving the " starry " effect 
referred to by Pliny. 

201 



Lapis lazuli usually occurs in 'limestone, but in connection with gran- 
ite, so that it seems to be a product of the eruption of the granite through 
the limestone. The lapis lazuli of best quality comes from Asia, the 
mines being at Badakschan, in the northeastern part of Afghanistan, on 
the Oxus River. The mining is done by building great fires on the rocks 
and throwing water on them to break them. The yield at present is 
small, not over 1,500 pounds a year being obtained. The lapis lazuli 
from these mines is distributed all over Asia, going chiefly to China and 
Russia. The price realized is said to be from $50 to $75 per pound. 
Lapis lazuli of poorer quality comes from a region at the western end of 
Lake Baikal in Siberia. The only other important locality is in the Andes 
Mountains of Chile near the boundary of the Argentine Republic. This 
material is not much used at the present time, on account of its poor 
quality, but it was employed by the Incas for decorative purposes. One 
mass 24x12x8 inches, doubtless from this locality, was found in a Peru- 
vian grave, and is one of the largest masses of lapis lazuli known. 

The walls of a palace at Zarskoe-Selo, Russia, built by order of 
Catherine II., are entirely lined with slabs of lapis lazuli and amber. 
Pulverized, the stone was used as a tonic and purgative by the Greeks 
and Romans, and as late as the sixteenth century was supposed to be a 
cure for melancholy. The name lapis lazuli means blue stone. Arme- 
nian stone is another term by which the stone is known in trade. 



202 



SMITH80NITE 

This mineral, named after James Smithson, who founded the Smith- 
sonian Institution in Washington, is a carbonate of zinc used chiefly as 
an ore of that metal. It is usually of a dull, earthy character and 
poorly fitted for ornamental purposes. In some occurrences, however, it 
exhibits pleasing colors and a translucency reminding one of onyx. 
When so occurring it may be cut into ring stones, or even vases and 
other dishes of considerable size and beauty. The smithsonite from 
Laurium, Greece, is that perhaps most extensively used in this way, its 
color usually being some shade of blue. From Siberia a beautiful bright 
green smithsonite is obtained, the green color being due probably to a 
little admixed copper, and from the zinc mines of Arkansas and Missouri 
a bright yellow form is derived, known locally as "turkey fat ore." 
The yellow color here is due to a little cadmium. All of these forms of 
smithsonite exhibit when polished a rich luster and subtransparency which 
are pleasing. The hardness of the mineral is somewhat deficient for 
enduring wear, this being but 5. It is rather heavy, its specific gravity 
being 4.3 to 4.4. It is infusible, but soluble in hydrochloric acid with 
effervescence. When heated before the blowpipe a coating is formed, 
which is yellow when hot and white on cooling. These tests serve to 
distinguish the mineral from any others with which it might be 
confounded. 



203 



ALABASTER 

(CALCITE, GYPSUM) 

The term alabaster is derived from a kind of ointment vases called 
alabastra, which the Egyptians and peoples of a later period were accus- 
tomed to carve out of stone. This stone was largely a stalagmitic calcite 
obtained at Thebes, but it is probable that gypsum was also used to some 
extent. At the present time the term is used loosely for either of these 
minerals when employed for the manufacture of ornamental objects, 
although stalagmitic calcite is now more generally designated as onyx. 

Both calcite and gypsum are soft minerals, the hardness of the 
former being 3, and that of the latter 2. They are not therefore fitted 
to endure wear, and can only be employed for objects such as vases, 
boxes, statuary, etc., not likely to be subjected to much attrition. Both 
stalagmitic calcite, however, and gypsum take an excellent polish, and 
preserve it if properly cared for. 

The term alabaster when referred to gypsum is limited to the fine- 
grained granular variety usually white or delicately shaded. It is 
obtained largely at Castelino, near Leghorn, in Italy, and is used for 
carvings of various sorts. Objects are often sold under the names of 
alabaster that have been made out of plaster of paris by molding. These 
can be distinguished from true alabaster by their lack of translucency. 

Another form of gypsum used for ornamental purposes is that known 
as satin spar. This is white, with a delicately fibrous structure, and 
exhibits when polished a beautiful silky luster and pearly opalescence. 
Large quantities of this cut in the form of necklaces, charms, etc., are 
often sold at Niagara Falls and vicinity to tourists as made from material 
found at the Falls. Although gypsum occurs there, it is not in this form, 
and the material used in this way is really obtained in Wales. 

Objects made from calcite can usually be detected by their softness, 
as they scratch easily and deeply with a knife, and by their effervescing 
when touched with a drop of any common acid. In the form of Mexican 
onyx calcite is extensively used for ornamental purposes, and many 
locally fashioned stones, such as the Petoskey, Michigan, fossil corals 
(often called agates), and the Gibraltar stone, of Gibraltar, belong to this 
mineral species. 

204 



r + +F 



.- 



*<*? J/?> 








AMB.EK, MALACHITE, LA-flS-LAZULI AND AZURITE. 



Lapis-lazuli, polished (Siberia). 



517 



Malachite and Azurite, polished (Arizona;. 
IMahichite, polished (Australia). 



Amber, polished, showing insects enclosed (Coast of Baltic Sea). 



Amber, rolled pebble (Coast of Baltic Sea). 

Malachite, polished (Ural Mountains). 
Malachite (Arizona). 



AMBER 

Few minerals have been longer in favor for ornamental purposes 
than amber. Among remains of the earliest peoples, such as the 
Egyptians and cave-dwellers of Switzerland, it is found in carved 
masses, indicating that it was highly prized. The Phoenicians are 
said to have sailed to the Baltic for the purpose of procuring it, 
while the Greeks' knowledge of it is indelibly preserved in our word 
electricity, derived from their word electron. 

Amber is a fossil gum of trees of the genus Pinus, and is thus 
a vegetable rather than mineral product. In color it is yellow, varying 
to reddish, brownish, and whitish. Its hardness is 2 to 2.5, it being 
slightly harder than gypsum and softer than calcite. It cannot be 
scratched by the finger nail, but easily and deeply with a knife. It 
is also brittle. Its specific gravity is scarcely greater than that of water, 
the exact specific weight being 1.05-1.096. It thus almost floats in 
water, especially sea water. It is transparent to translucent. On being 
heated it becomes soft at 150 C., and at 250 to 300 melts. It 
also burns readily and at a low temperature, a fact which has 
given rise to the name of bernstein, by which the Germans know 
it, and to' one of the Roman names for it, lapis ardens. Rubbed with 
a cloth it becomes strongly electric, attracting bits of paper, etc. As 
already noted, our word electricity comes from the Greek for amber, 
this seeming to be one of the first minerals in which this property 
was noted. Amber, being a poor conductor of heat, feels warm rather 
than cold in the hand, contrary to most minerals. It is attacked but 
slowly by alcohol, ether, and similar solvents, a property by which 
it may be distinguished from most modern gums and some other fossil 
ones. In composition it is an oxygenated hydrocarbon, the percentages 
of these elements being in an average sample: carbon, 78.94, hydro- 
gen, 10.53, and oxygen, 10.53. The mineralogical name of amber 
is succinite, a word derived from the Latin succum, juice. One of its 
constituents is the organic acid called succinic acid. 

The present source of most of the amber of commerce is the Prussian 
coast of the Baltic Sea, between Memel and Dantzig, although it is 
found as far west as Schleswig-Holstein and the Frisian Islands, and 

205 



even occasionally on the shores of Denmark, Norway, and Sweden. 
From time immemorial pieces of amber have been cast upon the shore 
in these localities, and their collection and sale has afforded a livelihood 
to coast-dwellers. Such amber is called sea stone, or sea amber, and 
is superior to that obtained by mining, since it is usually of uniform 
quality, and not discolored and altered on the surface. Owing to its 
lightness, the amber is often found entangled in seaweed, and the 
collectors are accustomed to draw in masses of seaweed and search 
them for amber. Amber so obtained is called scoopstone, nets being 
sometimes used to gather in the seaweed. In the marshy regions men 
on horseback, called amber riders, follow the outgoing tide and search 
for the yellow gum. It is also searched for by divers to some extent. 
From the earliest times the title to this amber has vested in the State, 
and its collecting has been done either under State control, or as at 
present, when a tax is levied by the government upon it. This tax 
is levied on the amber that is mined, as well as that obtained from 
the sea, and brings a revenue at the present time of about $200,000. 

Up to 1860 the methods of procuring amber were largely confined 
to obtaining it in the manner above noted. As it was evident, however, 
that the sea amber came from strata underneath, and that if either 
by dredging or mining these strata could be reached a much larger 
supply .could be obtained, exploration was carried on by mining methods 
with successful results, and the principal amount of the amber of com- 
merce is now so obtained. The strata, as shown in the mines of Sammland, 
the rectangular peninsula of East Prussia, where most of the mining 
is carried on, are : First, a bed of sand ; below this a layer of lignite 
with sand and clay; and following this a stratum of green sand, 
fifty or sixty feet in thickness. While all these strata contain scattered 
pieces of amber, it is at the bottom of the green sand layer that the 
amber chiefly occurs, in a stratum four or five feet thick, and of very 
dark color. It is called the " blue earth." This stratum is of Tertiary 
age, and there can be no doubt that its amber represents gum fallen 
from pines, which grew at this period, and whose woody remains are 
represented to some extent in the layer of lignite. It is probably true, 
as Zaddach remarks, that the amber has been collected here from older 
deposits. One of the most interesting proofs of the vegetable origin 
of amber is the occurrence in it of insects, sometimes with a leg or wing 
separated a little distance from the body, showing that it had struggled 
to escape. These insects include spiders, flies, ants, and beetles, and 
even the feather of a bird has been found thus preserved. Indeed, 
the amber deposits have furnished important contributions to our knowl- 

206 



edge of Tertiary life. Inasmuch as the pieces bearing such remains are 
valued more highly than ordinary amber, unscrupulous persons have 
at times found profitable employment in boring cavities into pieces 
of amber, introducing flies or lizards into them, and then filling up 
the hole with some modern gum of the same color. It is said that 
all amphibious or water animals seen in amber have been introduced 
in this way. 

Besides the counterfeiting of the inclusions of amber there are several 
substitutes for the gum itself. These are chiefly celluloid and glass, 
the substitution of the former being dangerous if used for the embel- 
lishment of pipes, on account of its inflammatory character. Celluloid 
can be distinguished from amber by the fact that when rubbed it 
does not become electric, and gives off an odor of camphor instead 
of the somewhat aromatic one of amber. It is also quickly attacked 
by alcohol, or ether, and when scraped with a knife gives a shaving 
rather than a powder, as amber does. Glass can be distinguished by 
its cold feeling and greater hardness and specific gravity. 

Besides these substitutes, it has been found possible by heating and 
pressing the scraps of amber not large enough for carving, to make 
them into a homogeneous mass, which is sometimes sold as amber 
and sometimes as amberoid. Amber is worked to desired shapes by 
turning it on lathes, or by cutting by hand. By heating it in linseed 
oil it becomes soft, so that it can be bent, and often all opaque spots 
can be made to disappear by such treatment. The amber which is 
most highly prized of any in the world comes from Sicily. Eight hun- 
dred dollars have been paid for pieces of this no larger than walnuts, 
making their value approach that of diamonds. The beauty of the 
Sicilian amber consists in the variety of colors which it displays, 
blood -red and chrysolite -green being not uncommon; and in the fact 
that these often exhibit a fluorescence, glowing within with a light 
of different color from the exterior. Chemically the Sicilian amber 
is not the same as the Prussian, as it contains less succinic acid, 
and is somewhat more soluble. In other respects it is not essen- 
tially different. It occurs chiefly on the eastern and southeastern coasts 
of the island, being washed up in a manner very similar to the Prus- 
sian amber. 

Amber has been found in several places in the United States, but 
there is little of commercial value. It is mostly connected with the 
Cretaceous glauconitic, or green sand deposits of New Jersey, fragments 
being frequently found there. This amber is of yellow color, but not 
so compact or lustrous as foreign amber. Amber has also been reported 

207 



from the marls of North Carolina, some of the coal-beds of Wyoming, 
and in connection with lignite in Alaska. In the latter region the 
natives are said to carve it into rude beads. 

Amber occurs in small quantities in several countries of Europe, 
such as near Basel, in Switzerland; near Paris, in France; and near 
London, in England. It is also found in many parts of Asia, these 
localities being a source of supply to the Asiatic countries, such as 
China and India. Occasionally amber is obtained from Mexico which 
has the beautiful fluorescence of the Sicilian article, though the exact 
locality whence it comes is not known. Specimens of carved amber 
are found among the relics of the Aztecs, and it is probable that they 
used it for incense. The early use of amber by European peoples has 
already been referred to. There are references to it in the most ancient 
literature, and worked masses of it are found among human relics 
of the greatest antiquity. Up to comparatively modern times it was 
an important article of commerce among widely scattered peoples, and 
had much to do with bringing about communication between them. 
Together with tin it was one of the chief objects which led the Romans 
to penetrate the Gallic regions to the west and north of the Mediter- 
ranean, and Pliny says that " it had been so highly valued as an 
object of luxury that a very diminutive human effigy made of amber 
had been known to sell at a higher price than living men, even in 
stout and vigorous health." One of the most elaborate of the Greek 
myths is that which accounts for the origin of amber. It runs in 
this wise: Phaethon, undertaking to drive the chariot of his sun-god 
father, Helios, lost control of his steeds, and approaching too near 
the earth set it on fire. Jupiter to stop him launched a thunder-bolt 
at Phaethon, and he fell dead into the Eridanus. His sisters lamenting 
his death were changed into poplars, and their tears became amber. 
According to another legend amber is the tears of the birds Meleagridae 
who weep for their brother Meleager. Moore refers to this legend in 

his lines: 

"Around thee shall glisten the loveliest amber 
That ever the sorrowing sea-bird hath wept." 

In the Odyssey one of Penelope's admirers gives her an amber 
necklace, and Martial compares the fragrance of amber to the fragrance 
of a kiss. Milton writes of amber, and Shakespeare mentions it both 
in "Love's Labor Lost" and "The Taming of the Shrew." 

Necklaces of amber are popular wedding presents among the peasants 
of Prussia. 

The properties assigned to amber, both as a charm and as a medicine, 

208 



have been many. From the earliest times it has been used as an amulet, 
being supposed to bring good luck and to protect the wearer against 
the evil eye of an enemy. Necklaces of amber beads are used to this 
day as preventive, or curative, of sore throat, and the Shah of Persia 
wears around his neck a cube of amber reported to have fallen from 
heaven in the time of Mohammed, which is supposed to have the 
power of rendering its wearer invulnerable. Amber was also taken 
internally in former times as a cure for asthma, dropsy, toothache, 
and other diseases, and to this day is prescribed by physicians in 
France, Germany, and Italy for different ailments. 

The use of amber for artistic and decorative purposes has declined 
considerably since the Middle Ages ; but magnificent illustrations of its 
employment for these purposes are to be seen in many European 
museums, notably the Green Vaults of Dresden. 

In this country a beautiful collection of objects made of amber is to 
be seen in the Boston Museum of Fine Arts. 

Though so soft and easily destructible a substance amber endures with 
ordinary care as well as the hardest stone, and many works of art 
formed from it are well preserved. 



209 



JET 

Jet is a variety of coal which, being compact, takes a good polish, and 
hence can be used in jewelry. Its hardness is between 3 and 4, and 
specific gravity 1.35. It is a kind of brown coal or lignite, and retain- 
ing as it does some of the original structure of the wood, is not brittle 
and smutty as is most coal. To be of the quality desirable for cutting 
it must be black, of a uniform color, and have a somewhat fatty luster. 

The jet of commerce has for a long time come chiefly from Whitby, 
Yorkshire, England. It occurs here as layers in schists of Upper Lias 
age. The industry of mining and cutting the jet has at times reached 
extensive proportions. In 1855 twelve hundred to fifteen hundred arti- 
sans were employed in the work, and the annual value of the output was 
$100,000. While Whitby is still the center of the industry, the demand 
for jet has considerably decreased, and the trade has suffered a serious 
setback. The jet manufactured in England is not all of local origin, 
much of it being obtained from France, Spain, Italy, Wurtemberg, and 
the Orient. Near the close of the eighteenth century considerable cut- 
ting of both foreign and domestic jet was carried on in France, but the 
industry is now largely abandoned. Good jet occurs in numerous locali- 
ties in America, especially in Colorado, and in Pictou, Nova Scotia, but it 
cannot be cut profitably to compete with the English product. In the 
anthracite coal regions of Pennsylvania this variety of coal is cut into a 
great variety of objects, which find a more or less extensive sale. Jet is 
employed chiefly for mourning jewelry. The decline in its use has come 
partly from a loss of its popularity and partly from the substitution for it 
of black onyx or black glass. These latter can be prepared somewhat 
more cheaply than jet, and while sometimes fraudulently substituted for 
that mineral, are often preferred when an opportunity for a choice is 
given. If it is desired to distinguish jet from either of these, it can be 
known by being softer and lighter, and by having a warmer feeling in 
the hand. Hard rubber and celluloid are also sometimes substituted for 
jet, in which case they can be distinguished by the fact that jet does not 
give a shaving under the knife, but crumbles away. The manufactured 
articles are usually also given their form by being pressed in molds, and 
by close inspection traces of the molds can be seen. 

210 



Jet seems to have been known to the Romans, their word for it 
being " gagat," of which jet is probably a corruption. The Greeks also 
prized the mineral, and considered it when powdered and mixed with 
wine a preventive of toothache. When mixed with beeswax they 
believed it to be a remedy for tumors, and burned as an incense it was 
supposed to drive away devils. 

Relics of the early Saxons also disclose numbers of jet ornaments, 
which show that it was in use among them. 

Jet is sometimes known as " black amber," a name not inappropriate 
when the similarity in origin of the two minerals is considered. 



211 



PEARL 

Pearl is not a mineral in the strict sense of the word, but has long 
been associated with gems in thought and use. 

Like amber, jet, and coral, pearls are a product of organic or living 
forces, not of inorganic nature. Mollusks, chiefly of the order of bivalves, 
are the organisms which produce pearls. They are a product, however, 
not of health and normal life, but of disease and abnormal conditions. 
This is well known by the pearl-fishers, so that, in searching for pearls, 
they pass by the young, well -formed mollusks, to gather only those 
appearing old, diseased, and distorted. The formation of pearls by a 
mollusk is generally believed to be the result of some persistent irrita- 
tion of the mantle. The agent of irritation has been thought to be a 
grain of sand, a bit of seaweed, an infusorian, a parasite, or an egg of the 
mollusk itself. The origin of the pearl has been supposed to be due to 
an effort on the part of the mollusk to protect itself from such an irri- 
tant as one of those above mentioned by secreting over it a calcareous 
deposit similar to that of which it forms its shell. 

Some recent investigations by Dr. H. L. Jameson of London go to 
show that many free pearls originate through the entry of a trematode 
worm into the epithelium of the mantle of a pearl-bearing mussel. The 
mussel, in order to protect itself against the parasite, deposits pearly 
matter around it. Even if the parasite leaves the mantle the formation 
of the pearl will continue. The life history of this parasite is interesting 
in that at different times it lives in three hosts. The first, in the region 
where Dr. Jameson studied it, is a so-called "tapestry shell," the second 
the pearl mussel, and the third two members of the duck family. The 
eggs of the parasite passing out with the faeces of the duck enter the 
body of the tapestry shell, then pass to the mussel, and when the latter 
is eaten by the duck, reach the intestine of the latter. This knowledge 
makes it seem likely that it will be possible ere long to infect pearl- 
bearing mollusks with the parasite in large quantities, and hence to 
greatly increase the production of pearls. 

The deposit of pearl has the color and character of the interior of 
the shell, or if the color of the shell varies in different portions, that of 
the part of the shell which is nearest. Unless the interior of the shell 

212 



possesses the peculiar nacreous luster desired in pearls, these will be 
of no value. 

The form and size of the pearls produced by mollusks varies con- 
siderably. Only those which are perfectly spherical or drop-shaped are 
considered of first quality for jewelry, but these are only a small part of 
the forms produced. Irregular protuberances or convexities often distort 
the spherical form, and highly complex and grotesque shapes occur. One 
such pearl is known having a remarkable resemblance to a bust of 
Michael Angelo. Others resemble insects or fruits. These resemblances 
can be enhanced by proper mounting and the addition of a little gold 
and enamel. Some fanciful work of this kind has been done, and a large 
collection of such pearls is preserved in the Green Vaults in Dresden. 
Such pearls are known as baroques, and formerly had comparatively 
little value, but at 
the present time they 
are being employed 
in the most costly 
jewelry. Not infre- 
quently the pearl be- 
comes attached to 
the interior of the 
shell, as is the one 
shown in the 
colored plate. Such 
pearls can be used by 
cutting them away 
from the shell, but 
they have much less value than those well formed on all sides. Loose 
pearls which form flat on one side are called button pearls, and are worth 
only about twenty-five per cent less than round pearls. Again, pearls may 
be hollow. Such are called coque de perle, and have little value if their hol- 
low nature be known. This, however, is not always the case, as is shown by 
an instance mentioned by Kunz, of a New York lady who had purchased 
a pearl apparently of good quality, except for a little black spot on one 
side. This was mounted and worn as an article of jewelry until, while 
its owner was applauding at the opera one evening, the pearl broke and 
disclosed its interior filled with a white, greasy clay. 

The Chinese take advantage of the habit of mollusks to cover any 
intruded substance with pearl, to introduce into the shells of these 
animals, under the mantle, beads and small images. The mollusk is 
returned to the water, and in about a year's time taken out again, when 

213 




Shell showing images of Buddha inserted during the life of 
a mollusk and then covered with a pearly deposit. After Kunz 



the objects are found to be coated with a pearly substance. Pearls so 
formed, however, are comparatively dark and lusterless, and have by 
no means the value of those of wholly natural origin. 

Pearls vary in size from those of microscopic dimensions to those as 
large as a pigeon's egg. The latter are, of course, very rare. 

The Shah of Persia is said to possess the largest pearl known, it 
being about one and one-third inches in length in one direction and one 
inch in another. A pearl in the Austrian crown weighs 300 carats, and 
one in the South Kensington Museum weighs 455 carats. The small 
pearls used in jewelry are known as seed, dust, or sand pearls. 

Pearls are chiefly white in color, but many are tinted yellow or pink; 
some are gray, green, or purple, and many other colors occur. Black 
pearls are obtained in certain fisheries. The pearls from the Unios of 
North America are of almost every shade. 

Pearls of pure white color, if of the proper luster, are those most 
highly prized in Europe and America, although a slight pinkish tinge 
does not injure the value. They must, however, have the transparency 
of the true pearl and not be " chalky." In China and India pearls of 
yellow color are preferred. 

The hardness of pearl is 4, and its specific gravity 2.65-2.68. It is 
thus like that of shell or " mother of pearl," which might be expected 
from the fact that both are of the same chemical composition carbonate 
of lime. Owing to their low hardness pearls are easily scratched, and on 
account of their composition are attacked by acids. They thus deterio- 
rate with age, losing their polish and luster and often becoming black and 
unsightly. No way of positively restoring the luster of pearls is known, 
although occasionally the outer marred coating can be removed by those 
skilled in the art, and a lustrous surface be found beneath. 

The Ceylonese are accustomed to feed pearls which have become dull 
to chickens. After the pearl has remained in the crop of the bird a few 
hours the fowl is killed and the pearl removed. The movement and 
friction to which the pearl has been subjected in the bird's crop are 
usually found to have restored its luster to some extent. 

To preserve pearls as long as possible they should be wiped with a 
clean linen cloth each time after being worn, and be kept in a dust-tight 
box carefully wrapped in linen. Hot or boiling water injures and in 
time destroys their luster, and many valuable pearls have been ruined 
because the mollusk which contained them was boiled before opening. 

The mollusks which yield pearls are many, and pearl-fishing is an 
industry carried on in many parts of the globe. 

The pearl mollusk or pearl oyster, par excellence, is that known by 

214 



the scientific name of Meleagrina (Avicula) margaritifera. This mollusk 
has a bivalve shell averaging seven or eight inches in diameter, and gen- 
erally thick. The exterior is of a greenish-black color, while the interior 
is silver -white with pearly luster. The latter forms indeed the well- 
known "mother of pearl." This mollusk inhabits warm seas, occurring 
especially in sheltered localities in the Indian Ocean, and occasionally 
throughout the tropical zone of the Pacific Ocean. It groups itself in 
colonies like the common oyster, usually on coral banks at a depth of 
twenty to thirty feet. It is not free moving, but attached by a byssus, 
which must be severed before the mollusk can be brought to the surface. 
The pearl fisheries of the Indian Ocean chiefly center in the Straits of 
Manaar between India and Ceylon. The fishing is largely confined to the 
months of March and April, as the sea favors best at that time, and at 
that season from fifteen thousand to twenty thousand fishers and dealers 
are said to gather along the pearl coasts. The oysters are obtained by 
divers, who go out in boats and secure the shells by diving. They 
usually dive without appliances, and work under the water simply by 
holding their breath for the time. Some fishers, however, make use of 
diving suits and bells. The work is dangerous, not only on account of 
the bodily strain, but because sharks prey upon the divers. The oysters 
are unloaded from the boats into pits on the shore, where they are left 
to putrefy, and the pearls are then washed out. 

Other localities in the Orient where the pearl oyster occurs, and 
where pearl-fishing is carried on in the same manner as above described, 
are the Persian Gulf, the Red Sea, and the Sulu Archipelago. The Red 
Sea fisheries furnished in earlier times an extensive supply of pearls, and 
were probably the source of those used by the Romans. They are now, 
however, largely exhausted. The Persian Gulf pearls are inferior in color 
to those of Ceylon, and are known as "Bombay" pearls. The Ceylon 
fisheries are under control of the colonial government, and are carefully 
guarded to prevent exhaustion of the supply. The localities where the 
fishers are to work are staked off, and when an area has once been 
worked over it is allowed to lie "'fallow" for seven years, so as to allow 
a new crop to grow. 

So far as the American continent is concerned, the true pearl oyster 
is found chiefly in the Gulf of California. It occurs here both on the 
east and west coast, and as far south on the Pacific coast as the northern 
boundary of Guatemala. It is also found on the Brazilian coast and 
the western shores of South America. 

The California pearl fisheries were in operation at the time of the 
invasion by Cortez, and he sent a number of fine pearls which he 

215 

\ 






obtained there to the queen of Spain. Since that time the fisheries 
have been carried on with a varying degree of persistence from time 
to time, the beds having occasionally become practically sxhausted 
through too reckless dredging. The right to work the beds is held 
by the Mexican government, and the fisheries are leased by it to differ- 
ent companies. Both the shells and the pearls are of value, the sales 
of the one reaching as high a figure as of the other. Black pearls 
are the specialty of these fisheries, and some of the finest known 
have been found here. The total annual product from the fisheries 
reaches at the present time a value of half a million dollars a year. 
American pearls are known in trade as "Panama" pearls, and bring 
a somewhat lower price than those of the Orient. 

Besides the pearl oyster of the sea, a number of mussels which 
make their home in the beds of fresh-water streams or lakes produce 
fine pearls. These mollusks belong chiefly to the family Uwonida, 
and include many species. They are bivalves, and live both in the 
beds of running streams and in still bodies of water on muddy bottoms. 
They are usually to be found at a depth below the surface of the water 
of from two to twenty feet. They lie either on the surface of the 
mud, or partly imbedded in it, and with their valves slightly open, 
to allow access of water containing oxygen and food. At the slightest 
touch the valves close, and remain so until danger is past. The lumber- 
men of Canada take advantage of this peculiarity to collect the mollusks 
for food by tying bushes on the rear of their rafts as they float down 
stream, to which the clams attach themselves in considerable num- 
bers. A somewhat similar method is pursued by the fishermen of the 
Mississippi Valley, who collect the clams in great numbers for the 
manufacture of pearl buttons. They row about with long iron rods 
fastened across their boats, from which at intervals series of hooks 
and chains dangle in the water, and to these the mollusks attach 
themselves. The mollusks are removed from their shells by boiling, 
hence any pearls which they might contain are rendered worthless. 
The same method of fishing might, however, be used to gather shells 
for pearls. Other methods used to gather the mollusks to search for 
pearls are: raking the bottom with an iron rake; wading with naked 
feet, and picking up any projecting shell as it is felt; or systematic 
dredging. The use of a water telescope is said to facilitate the work 
of individual search for mollusks likely to contain pearls. It consists 
simply of a long, light, wooden box, one end of which is strapped 
to the face, while the other, covered with glass, is immersed in the 
water. Provided with this appliance the bottom of a river or lake can 

216 



be searched carefully. Enormous quantities of the Unios are destroyed 
in the search for pearls, and the supply has become considerably 
diminished in consequence. This waste might be avoided if care was 
used in opening the shell not to injure the animal. This work is per- 
formed in Germany by a thin blade of steel about an inch in width, 
and bent at a right angle about an inch from the end. The thin 
blade is inserted between the valves, and then turned at right angles 
so that the shell is opened the width of the blade. The operator can 
then feel about for pearls, and if none are found return the mollusk 
to the water without having injured it. The search for pearls in this 
country is usually carried on by persons out of regular employment, 
and has rarely been reduced to a systematic occupation. The total 
value of the pearls which have been obtained, however, is great, and 
their price is steadily increasing. One of the first valuable pearls found 
in this country was obtained near Paterson, New Jersey, in 1857. This 
pearl brought at its first sale $2,500, and is to-day worth $10,000. 
A sky-blue pearl weighing ninety-three grains, found at Caney Fork, 
Tennessee, in 1897, was sold in London for $3,300. Pearls valued 
at from $100 to $1,000 are frequently found in the waters of the 
interior States, such as Wisconsin, Minnesota, and Arkansas. In Arkansas 
large numbers of valuable pearls have been found loose in the streams, 
so that many of the pearl-hunters are of the opinion that the mollusks 
" shed " their pearls at intervals. While the region of the Mississippi 
Valley is that in which the pearl -bearing mollusks chiefly abound, 
they occur also in the waters of the Eastern States, and these furnish 
an appreciable supply. 

The common oysters and clams of the temperate sea coasts pro- 
duce pearls no less than those of fresh waters; but they lack the 
desired luster and transparency, and are considered of no value. Some 
gastropod, or univalve mollusks, also produce pearls, among which 
may be mentioned the Strombus of the West Indies and the Turritella 
of the East Indies. These pearls are of rose tint, but are liable to fade, 
and lack also the transparency of the true pearl. 

Pearls seem to have been valued by peoples of all times, both civilized 
and uncivilized. The Hebrew Scriptures make frequent references to 
them, and there are many incidents in history showing the esteem 
in which they were held by the Greeks and Romans. The best known 
of these is probably Cleopatra's wager with Antony, that at a single 
meal she would swallow the value of a whole province. In pursuance 
of this boast she is said to have dissolved a pearl of great value in 
a glass of sour wine, and then to have drank the wine. It may be 

217 



worth noting that this story cannot be literally true, since a pearl 
of the size reported would only slightly dissolve in such a mixture. 
If ground to a fine powder, however, the pearl might be swallowed 
in the wine without injury to the system, and if this was done the 
story can be credited. According to Pliny the wealthy Romans were 
accustomed to mix pearls with their wine, presumably in this way, 
to improve the flavor of the beverage. The name for the pearl among 
the Romans and Greeks was Margarita, and the finest pearls are still 
known by this term. 

The Romans believed that pearls were solidified drops of dew, 
which had fallen into the gaping shells of oysters. The size and 
quality of the pearl were supposed to depend on the size of the dewdrop 
and the purity of the air. Ancient Hindoo authorities describe pearls as 
originating in elephants, clouds, boars, fishes, frogs, and oysters, the latter 
being the most productive. In their view the effect of the pearl upon its 
wearer varied with its color. A light yellow pearl brought wealth, one 
more deeply colored, understanding, a white pearl, fame, and a blue one, 
good luck. 

Among the Chinese and Hindoos to this day pearls are regarded as 
of great medicinal value, and a large proportion of the imperfect pearls 
obtained in the fisheries are used for this purpose. They are considered 
beneficial in syncope, hemorrhage, and stomach troubles, and seed pearls 
are mixed with sweetened water for use as a stimulant. Among the 
Arabians and Persians pearls are used as a cure for insanity and all 
mental diseases; for diseases of the heart, stomach, and bowels; and for 
bleeding and skin diseases. A similar belief in the efficacy of pearls for 
the cure of insanity existed in Europe as late as the seventeenth century. 
The insane King of Spain, Charles, was given pearl powder mixed 
with distilled water as a remedy. The Aztecs and Incas of America, 
when first visited by the Spaniards, possessed quantities of pearls of the 
finest luster and color. Large numbers of pearls are found in the 
prehistoric mounds of America also, showing that even these people 
held them in esteem. These pearls generally lack the luster of the 
pearl of the present day ; but whether this has been lost through lapse 
of time, or whether the Mound Builders were content with pearls that 
would to modern people seem valueless, is not known. The mound 
pearls are frequently found bored and strung. 

The passion for pearls for ornament continues at the present day, 
and they often command even higher prices than the diamond, weight 
for weight. The price, however, depends so much upon individual 
quality that no fixed scale of values can be given. 

218 



Emanuel gives the following qualifications, as necessary to a per- 
fect pearl: " . 

1. It must be perfectly round, or drop-shaped, seeming as if fashioned 
or turned into shape. 

2. It must have a perfectly pure white color. 

3. It must be slightly transparent. 

4. It must be free from specks, spots, or blemish. 

5. It must possess the peculiar luster characteristic of the gem. 
Pearls are sold by their weight in 

grains, rather than by carats, four grains 
equaling a carat. Seed pearls weighing 
one grain are usually worth from one to 
three dollars each. With the increase 
in size, however, the increase in price is 
rapid, a two-grain pearl being worth, for 

instance, four times as much as a one- 

grain pearl, a three-grain pearl nine ^*^ " 

times as much, and so on. The largest 






pearls bring, like the largest diamonds, 

individual prices. The pearl is, per- ^^ ^^ 

haps, the only gem that does not need ^P ^BF 

to have its beauties enhanced by cutting, ^^_ ^^_ 

nor can any polishing process improve ^J 

its surface. The favorite use of pearls ^^ 

20 ^A 22 

is to string them in necklaces ; but they ^^v 

are also often set around other stones ^^^ 

to heighten their effect, or they are used 2B W 
alone in rings. 

There are numerous ways of pro- Bx ct sizes^of^earjsfrom 2 to 30 

ducing imitation pearls, one of which, 

invented many years ago by a French bead-maker named Jacquin, gives 
remarkably accurate reproductions. The Jacquin pearls are made from 
an easily fusible bluish glass, which is first drawn into tubes, and from 
these, hollow globules of the desired size are blown. These are covered 
on the inside with a solution of isinglass, and a substance called essence 
of pearl, which is blown in warm, and spread over the interior by 
rapid motion. When dry, the globules are filled with wax. The essence 
of pearl, which constitutes the important feature of Jacquin's process, 
consists of a silvery substance found beneath the scales of the fish 
known as the bleak (Cyprinus alburnus). It is in the form of thin, 
irregular rhombic plates, and is obtained by washing the scales, one 

219 



pound of essence being derived from seven pounds of scales. From 
eighteen thousand to twenty thousand fish are required to produce 
the latter amount of scales. The substance is, therefore, costly; and 
owing to this fact, and the amount of labor and skill required to make 
the pearls, they bring a considerable price. They can be distinguished 
from genuine pearls by their greater hardness, and a colder feeling 
in the hand. The holes in the false pearls, moreover, are comparatively 
large, and have a blunt edge, while those made in real pearls are small, 
and have a sharp edge. False pearls are sometimes made by turning 
pieces of mother-of-pearl into a spherical form; but they are clumsy 
imitations, and can be at once detected by the difference of luster 
as a whole, and the variations of luster on different surfaces. A very 
good imitation of black pearls is made by cutting pieces of hematite 
into a spherical form. These counterfeit the luster of the black pearl 
in a remarkable degree; but can be distinguished by their greater 
weight and hardness. 



220 




Dredging Precious Coral 



PRECIOUS CORAL 

Of the great number of forms and species of coral known a single 
one furnishes nearly all that is used in jewelry. This species is known 
by the scientific name of Corallium rubrum, and belongs to the family 
Gorgonidae of the group Alcyonaria. It is a branching coral, shrub-like 
in its appearance, and grows to a height of a foot or more, with stems 
an inch in diameter. If the living coral be examined it will be found 
to consist of an outer fleshy or gelatinous portion inclosing an inner, 
hard, calcareous skeleton. The outer portion is made up of numbers of 
polyps, as the little coral animals are called, joined together. The pro- 
jecting polyps look in life like little warts over the surface. Each has 
eight tentacles. The internal skeleton differs from that of the majority 
of corals in being red in color. When the coral animals die this internal 
skeleton is left, and by polishing it the coral of jewelry is obtained. This 
kind of coral grows almost exclusively in the Mediterranean Sea. The 
localities where it is most abundant are the coasts of Algiers and Tunis, 
the western coasts of Sardinia and Corsica, portions of the coast of 
Sicily, the western coast of Italy, and a few localities on the southern 
coasts of France and Spain. The coral forms banks at depths of from 
ninety to one hundred feet, growing up from the bottom. That of the 
greater depths has not as rich color as that nearer the surface, and does 
not grow to so large a size. The work of dredging the coral is per- 
formed by fleets of small vessels manned by crews of from six to twelve 
persons. Work is carried on only in the summer months because of the 
stormy weather at other seasons. The vessels are obliged to put out 
about six miles to sea in order to reach the best fishing-grounds, and the 
work is of a laborious and dangerous sort. The dredging is performed 
by means of an appliance consisting of two heavy oaken sticks bound 
together in the shape of a cross, from the ends of which hang ropes 
upon which are fastened nets with meshes of different sizes. On being 
sunk to the bottom by means of a heavy stone, the nets of the dredge 
entangle branches of coral, or they are attached by divers, and upon 
drawing to the surface the coral can be picked off. The price obtained 
for the raw coral is from four to seven dollars per pound, each vessel 
securing from three hundred to four hundred pounds in a season. 

221 



The industry is almost exclusively in the hands of Italians, although 
originally carried on by the French. The latter are said to be striving, 
by means of subsidies and in other ways, to regain control of the indus- 
try, especially on the Algerian coasts. The production from this region 
alone amounts to twenty-two thousand pounds yearly. The cutting 
and working of the coral is carried on chiefly in factories in the cities 
of Genoa, Leghorn, and Marseilles. The value of the crude coral 
varies considerably according to its quality. If the coral polyps have 
died before a branch is brought to the surface, the coral turns black, 
and its value is thus considerably decreased. On /the shores of Sicily 
a large proportion of dead coral is brought up, and the proportion 
is continually increasing. The cause is believed to be quantities 
of volcanic ash thrown from the neighboring volcanoes, which make 
the water too muddy for the polyps. Some of the coral found is con- 
siderably worm-eaten, and this sort is highly valued in some parts 
of India, although regarded worthless in Europe. The particular shade 
of coral most highly valued by Europeans varies from time to time. 
At one time the bright red was preferred, then a pale pink, or rose color, 
came into fashion, and now the red seems to be most in favor again. 
The color, whatever it is, should be uniform to make a piece of coral 
of the best quality. The forms into which coral is cut include beads, 
buttons, ear-ring drops, cameos, and carvings of various sorts. Polished 
pieces of branches an inch or two in length are often worn in bunches, 
either as brooches or in the form of bracelets and necklaces. These 
were supposed in former times to act as a charm to ward off bad luck 
and evil spirits. Coral is especially prized by dark-skinned people, 
such as the Italians, Moors, Persians, and Hindoos, because its color 
harmonizes well with their complexion. The Chinese also use immense 
quantities of it, although the effect in color, as contrasted with that 
of the wearer, is less favorable to them. 

Precious coral seems to have been known and prized by the Greeks 
and Romans. The Greeks called it gorgeia, and believed that it 
originated from the blood which dripped from the head of Medusa, 
and which becoming hard was planted by sea-nymphs in the sea. 
In the Middle Ages precious coral was used in medicine as an as- 
tringent, and was given to newly born infants. It was also given 
together with a preparation of pearls as a cure for vomiting and 
colic. It was supposed to be a heart stimulant and to cure fevers 
and poisonings. Hung on fruit-bearing trees it protected them from 
hail and blighting winds and gave fertility. It was worn by 
children as a preventive against children's diseases, and infants were 

222 



supposed to be protected in their sleep by having a piece tied round 
their necks. 

To this day the Brahmins and Fakirs of the East place coral upon 
their dead to prevent evil spirits taking possession of the corpse, while 
in Egypt it is taken internally as a tonic after being treated with lemon 
and burned. 

Coral is imitated in celluloid, also by a mixture of marble dust cemented 
with glue, and stained with vermilion. Beads of bone and of gypsum 
are also stained so as to imitate coral. These imitations can be distin- 
guished by chemical and physical characters, true coral having a specific 
gravity of 2.6-2.7, and a hardness of nearly 4. It also effervesces 
with weak acid, which would not be the case with two of the above 
imitations. 




223 



INDEX 



Abrasives 
Achroite - 
Adamantine luster 
Adularia 
Agate 

cutting of 

Petoskey 
Alabaster 
Albite 

Alexandrite - 
Allanite 

Almandine ruby 
Almandite 
Amazonstone 
Amber 

black 

imitations of 

mining of 
Amethyst 

Amorphous substances defined 
Andalusite 
Andradite 
Anisotropic media 
Apatite 

Apostolic gems - 
Aquamarine 
Armenian stone 
Asparagus stone 
Australia, diamond fields of 

opals of - 

sapphires of - 
Austrian Yellow diamond - 
Aventurine 
Axinite- 
Ax-stone 
Azurite 

Balas ruby 
Baroque pearls 
Basanite 
Bernstein 
Beryl 

caesium - 

golden 
Billitonite 
Birthstones 
Black amber 



PAGE 

- 47 

111 

16 
179 
154 

48 

204 

204 

178 

106, 107 

- 140 

95 

- 127 
176 

- 205 
211 

- 207 
207 
145 

40 

- 124 
127 

- 26 
185 

65 
98, 102 

- 202 
185 

85 
163 

- 93 
74 

149, 179 
139 

- 167 
198 

95 
213 

- 158 
205 

98 
103 

98, 103 
184 

61 
211 



PAGE 

Black opal - 163 

pearl - 216, 220 

Blue ground - 83 

Blood stone 153, 188 

Blue-John 187 

Bombay pearl - - 215 

Bone turquois 170 

Borneo, diamond fields of 85 

Bort - 68 

Bowenite - 196 

Braganza diamond - - 83, 121 

Brazil, agate of - - 154 

amethyst of 145 

andalusite of - 124 

chrysoberyl of - 106 

diamond fields of 75 

euclase of 104 

rock crystal of - 143 

topaz of - 121 

Brazilian chrysoberyl - - 106 

chrysolite 111 

diamond - 142 

emerald - 111 

sapphire - 111 

Brilliant, double - 46 

form of - 44 

mixed 45 

sizes of - 51 

Briolette 46 

British Guiana diamond fields - 86 

Bronzite - 169 

Burmah, jade of - 165 

ruby of - 89 

Button pearls - - 213 

Cabochon cut 46 

Cacholong - 160 

Caesium beryl 103 

Cairngorm stone - 147 

Calcite 204 

California, diamonds of - 87 

tourmaline of - 116 

Callainite - 174 

Cape chrysolite 193 

Cape ruby - 129 

Carat defined 50 

Carbonado - - - - 68 



225 



Carbuncle 

Carnelian 

Carnelionyx - 

Cascalho 

Cat's-eye - 106, 107, 

Ceylon, chrysoberyl of 

essonite of 

gem cutting in - 

gem mining in 

pearl fisheries of 

sapphire of - 

spinel of - 

zircon of 

Ceylonese chrysolite 
Ceylonite 
Ceylon opal - 
Chalcedony 
Chalcedonyx 
Chalchihuitl 
Chiastolite - 

Chlorastrolite ... 
Chloromelanite 
Chrysolite 
Chrysoberyl 
Chrysocolla 
Chrysoprase 
Cinnamon stone 
Citrine 

Colombia, emeralds of 
Colors of gems 

as seen with the dichroscope 
Coral 
Cordierite 
Corundum - 
Critical angle 
Crocidolite - 
Cryptocrystalline quartz 
Crystal forms 
Cube 

Cutting of gems 
Cyanite - 
Cymophane - 

Demantoid 
Demidovite - 
Derbyshire spar 
Dewey diamond 
Diamond 

artificial production of - 

Australian 

Austrian Yellow - 

Braganza 

Brazilian - 

British Guiana 

cleaning of - - 

colors of 



PAGE 
130 

- 151 
156 

10, 75 

148, 169 

106 

- 130 

42 
8 

215 
93 
96 

- 109 
132 

96 
178 
150 
156 

- 167 
124 

- 191 
165 

- 132 
106 

- 199 
152 

- 127 
147 

- 100 

13 

33 

221 

- 136 

88 

28 

149 

- 150 

37 

- 39 
41 

- 123 
106, 107 

- 130 
199 
187 

86 
66 
87 
85 
74 

83, 121 
75, 142 

- 86 
82 
68 



PAGE 

Diamond, combustibility of 66 

crystal form of . 67 

cutting of - 47 

Dresden Green - - 68 

Excelsior - 83 

Florentine - - -68, 74 

Great Mogul - 74 

hardness of - - - - 69 

Hope Blue - - 68 

of India - - 71 

Jubilee - 83 

Kohinoor - - - - 72 

Lake George - - 142 

luster of - 68 

Matura - 109 

mining of - 77 

of United States 86 

of Ural Mountains - - 85 

origin in Brazil - 80 

origin in South Africa - 84 

Orloff - 73 

Pitt - 72 

Regent - 72 

Sancy 74 

slaves' - 120 

sorting of - - 11, 82 

South African - 80 

specific gravity of - 69 

Tiffany 83 

Victoria - 83 

Dichroism - 31 

Dichroite - 136 

Dichroscope 33 

Diopside - 16$ 

Dioptase - 200 

Dispersion - 27 

Dispersive power - 27 

Disthene - 123 

Distortion of crystals 37 

Distribution of gems - 7 

Dodecahedron 40 

Double brilliant 46 

Double refraction - 29 

Doublets - 56 

Dresden Green diamond - 68 

Effect of heat on color of gems - 14 

Emerald 98, 99, 158 

confused with jade - - 101 

Enstatite 169 

Epidote - 134 

Eruptive rocks 6 

Essonite - 127 

Euclase 104 

Euxenite - - 140 

Excelsior diamond - 83 



226 





PAGE 




False amethyst - 


186 


Iceland agate 


chrysolite 


132 


Idocrase 


emerald ... 


186 


Imitation coral - 


lapis - 


157 


gems 


ruby 


186 


pearls 


topaz - 


186 


Indicolite 


Feldspar 


175 


India, bloodstone of 


Fergusonite - 


140 


carnelian of 


Fire opal 


161 


diamonds of 


Flame opal - 


161 


garnets of 


Flint 


158 


moss agate of 


Florentine diamond - - 68, 


74 


lolite 


Fluorescence - - 35, 


186 


Isotropic media 


Fluorite 


186 


Israelitish gems 


Fluorspar 


186 


Itacolumite 


Fool's gold - 


189 




Fowlerite 


194 


Jacinth 






Jade 


Gadolinite - 


140 


Jadeite 


Gagat - 
Garnet 
Gems, apostolic 


211 
127 

65 


Jargon 
Jargoon 
Jasper 


distinguished from precious stones 


3 


Jet - 


Israelitish 


65 


Job's tears 


mining of - 8, 


12 


Jubilee diamond 


mounting of - 


48 




nature of - 


1 




occurrence of - 


4 


Kohinoor diamond 


Scriptural .... 


61 


Kunzite 


valuation of - 


50 




Gem gravels - 5, 9 


Labradorite 


Geyserite 


160 


Lake George diamonds 


Gibraltar stone - 


204 


Lapis lazuli 


Girasol 


161 


Lepidolite - 


Golden beryl - 98, 


103 


Leucosapphire - 


Golden opal - 


161 


Love's arrow 


Great Mogul diamond - 


74 


Luster of gems, 


Green star stone - 


191 


Lydian stone 


Grossularite 


127 


Lyncurion 


Gypsum 


204 








Malachite 


Hair stone 


148 


Marcasite 


Hardness of gems - 


17 


Marekanite 


Harlequin opal - 


161 


Matura diamond 


Hawk's-eye - 


149 


Menilite 


Heavy liquids - 


21 


Mesolite 


Heliotrope 


153 


Metallic luster - 


Hematite 188, 


220 


Metamorphic rocks - 


Hiddenite - - 


118 


Methylen iodide - 


Honduras, opals of - 


163 


Mexican onyx 


Hope Blue diamond 


68 


Mining of gems - 


Hornstone ... 


158 


Mocha stone 


Hungarian opals 


162 


Moldavite 


Hyacinth 109, 110, 


116 


Moonstone - 


Hyalite 


160 


Moss agate 


Hydrophane - 


160 


Mountain mahogany 


Hypersthene 


169 


Mounting of gems 




227 



PAGE 
182 

135 
223 
54 
219 
111 
153 
152 
71 
129 
151 
136 
26 
65 
80 

109 

- 165 
165 

- 109 
109 

- 157 
210 

- 133 

83 

- 72 
118 

- 176 
142 

- 201 
117 

88, 94 

148 

16 

158 

- 110 

- 197 
190 

- 181 
109 

- 160 
192 

- 16 

6 

- 22 
156 

- 8,12 

151 

- 183 
178 

- 151 
181 

- 48 





PAGE 




PAGE 


Nature of gems 


1 


Phenocrystalline quartz 


- 141 


Needle stone 


- 148 


Phosphorescence 


34 


Nephrite ... 


165 


Pitt diamond ... 


- 72 


Nicol prism ... 


29 


Plasma 


153 


Nigrine 


137 


Pleochroism 


- 31 






Pleonaste 


96 


Obsidian 


- 180 


Polarization ... 


29 


Occurrence of gems 


4 


Polarizing apparatus 


30 


Octahedron 


39 


Polycrase 


- 140 


Odontolite ... 


170 


Pomegranate ruby - 


97 


Oeil-de-boeuf 


- 177 


Prase 


152 


Oily luster - 


16 


Precious stones defined 


3 


Oligoclase ... 


- 179 


Prehnite 


193 


Olivine ... 


132 


Pseudo-emerald 


198 


Onyx .... 


156, 204 


Pyrite 


- 189 


Mexican ... 


156 


Pyro-electricity 


34 


Opal 


- 159 


Pyrope - 


127 


black ... 


163 






fire - ... 


- 161 


Quartz 


141 


flame ... 


161 


aventurine 


- 149 


golden ... 


- 161 


cryptocrystalline 


150 


harlequin 


161 


phenocrystalline 


- 141 


resin - 


- 160 


rose 


146 


wax ... 


160 


rutilated 


148 


Oriental amethyst 


- 88 


eagenitic 


148 


aquamarine 


88 


smoky 


147 


chrysolite ... 


88, 106, 132 






emerald 


88, 93 


Radio-active gems - 


35 


hyacinth - 


- 88 


Refraction 


- 26 


topaz ... 


88 


Regent diamond 


72 


Orloff diamond 


- 73 


Resin opal 


- 160 


Ox-eye ... 


177 


Resinous luster 


16 






Rhinestone 


142, 143 


Panama pearls ... 


- 216 


Rhodonite - 


194 


Paste ... 


55 


Rock crystal 


- 141 


Pearl - - 


- 212 


Rose cut 


46 


baroque 


213 


Rose quartz 


- 146 


black ... 


216, 220 


Rubicelle 


95 


Bombay - 


215 


Rubellite 


111, 116 


button 


- 213 


Ruby 


89 


fishing ... 


- 215,216 


almandine 


95 


fresh water - 


- 216 


artificial production of - 


91 


Oriental 


215 


Balas 


- 95 


origin of - 


212- 


Cape 


129 


oyster 


215 


pomegranate 


- 97 


Panama 


216 


value of - 


89 


preservation of - 


214 


Ruby spinel 


95 


size of 


- 214 


Rutile 


137 


use in medicine - 


218 


Rutilated quartz 


- 148 


Pearly luster 


- 16 






Pendeloque - 


46 


Sagenite 


148 


Penfield specific gravity balance 


- 21 


Sagenitic quartz 


148 


Peridot 


132 


Sancy diamond 


74 


Peristerite 


- 178 


Sapphire d'eau - 


136 


Petoskey agate 


204 


Sapphire 


92 


Piezo-electricity 


- 34 


of Australia - 


- 93 


Phenacite 


105 


of Montana 


93 



228 



Sapphire of Siam 

star 

water 

Samarskite - 
Sard 
Sardonyx 
Satin spar 
Saxon topaz 
Saxon chrysolite 
Scale of hardness - 
Scepter diamond 
Schorl 

Scriptural gems 
Sedimentary rocks - 
Semi-precious stones defined 
Serpentine - 
Siberite - 
Silky luster - 
Single refraction 
Slave's diamonds 
Smithsonite 
Smoky quartz 
South Africa, diamonds of 

tiger eye of 
Spanish topaz - 
Specific gravity 
Spessartite 
Sphene 
Spinel 

Spinel ruby - 
Spodumene 

Star of South Africa diamond 
Star of the South diamond 
Star sapphire 
Step cut - 
Strass 

Stream beds 
Sunstone 

Superstitions regarding gems 
Systems of crystallization - 

Table cut 

Table of color 

Table of hardness 

Table of specific gravity 

Thomsonite 

Thoulet solution 

Thulite - 

Tiffany diamond 

Tiger-eye 

Titanite 



PAGE 




PAGE 


- 


93 


Topaz 


119 




94 


Brazilian 


120 


- 


136 


Oriental 


88, 121 




140 


Russian - 


121 


- 


152 


Saxon 


- 121 




156 


Spanish - 


147 


- 


204 


Touchstone 


- 158 




121 


Tourmaline - 


111 


- 


132 


colors of 


- 114 




17 


composition of 


113 


- 


74 


localities of - 


115, 116 




111 


Trap cut 


45 


- 


61 


Trapezohedron - 


40 




6 


Turkey-fat ore 


203 





3 


Turquois 


- 170 




195 


of Persia 


171 


. 


111 


of United States 


- 171 




16 


Tuscan diamond 


74 


. 


29 








120 


Ultramarine 


201 


_ 


203 


United States, occurrence of 


dia- 




147 


monds in 


86 


. 


80 


turquois of - 


- 171 




149 


Uralian emerald 


131 


121, 


147 


Ural Mountains, aventurine of - 


- 150 




19 


chrysoberyl of 


107 


. 


127 


diamond fields of 


85 




138 


euclase of 


104 


. 


95 


garnet of 


- 130 




95 


malachite of 


198 


. 


118 


topaz of 


- 121 




83 


tourmaline of 


116 


. 


80 


Uvarovite 


- 127 




94 






a 


45 


Valuation of gems 


50 




55 


Variscite - 


- 174 


. 


4 


Vermeille 


129 


178, 


179 


Vesuvianite 


135 




57 


Victoria diamond - 


83 




38 


Viluite - 


- 135 






Vitreous luster 


16 


- 


46 
15 


Water sapphire - 


- 136 




JUf 

1H 


Wax opal 


160 




xo 

25 


Waxy luster 


16 




4M 


Williamsite - 


196 


- 


192 








22 


Xanthite 


- 135 


- 


195 


X-rays 


35 


68, 


83 






- 


148 


Zircon 


- 109 




138 


Zoisite ... 


195 




14 DAY USE 

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